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Set up an expression and compute in order · 12 practice problems

3.OA.A.33.OA.D.8

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Generated variants — 12

Freshly produced from the archetype’s parameters — problem, figure, and solution derived together.

Variant 1 easy

One eraser costs $\$1.20$ and one pair of scissors costs $\$1.30$ . The teacher wants to give every one of the $15$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 15 students gets one eraser ($1.20) and one pair of scissors ($1.30). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $1.20.
One pair of scissors costs $1.30.
There are 15 students, each getting one of each item.

Unknowns

The total money needed to buy 15 erasers and 15 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 15. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$1.20 + \$1.30 = \$2.50

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 15 students

#8 Analyze the Units 3.OA.A.3

Each of the 15 students costs $2.50, so multiply $2.50 by 15 to get the total.

\$2.50 \times 15 = \$37.50

Equal groups of money means repeated addition, which is multiplication.

Answer: $37.50

4 · Reviewdoes it hold up?

Each student costs about $3, and $3 times 15 is about $45. Our exact answer $37.50 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 15 erasers cost $\$1.20 \times 15 = \$18.00$ and 15 pairs of scissors cost $\$1.30 \times 15 = \$19.50$ ; their sum is $37.50.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 2 easy

One eraser costs $\$0.75$ and one pair of scissors costs $\$0.80$ . The teacher wants to give every one of the $20$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 20 students gets one eraser ($0.75) and one pair of scissors ($0.80). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.75.
One pair of scissors costs $0.80.
There are 20 students, each getting one of each item.

Unknowns

The total money needed to buy 20 erasers and 20 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 20. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.75 + \$0.80 = \$1.55

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 20 students

#8 Analyze the Units 3.OA.A.3

Each of the 20 students costs $1.55, so multiply $1.55 by 20 to get the total.

\$1.55 \times 20 = \$31.00

Equal groups of money means repeated addition, which is multiplication.

Answer: $31.00

4 · Reviewdoes it hold up?

Each student costs about $2, and $2 times 20 is about $40. Our exact answer $31.00 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 20 erasers cost $\$0.75 \times 20 = \$15.00$ and 20 pairs of scissors cost $\$0.80 \times 20 = \$16.00$ ; their sum is $31.00.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 3 easy

One eraser costs $\$0.95$ and one pair of scissors costs $\$1.05$ . The teacher wants to give every one of the $20$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 20 students gets one eraser ($0.95) and one pair of scissors ($1.05). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.95.
One pair of scissors costs $1.05.
There are 20 students, each getting one of each item.

Unknowns

The total money needed to buy 20 erasers and 20 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 20. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.95 + \$1.05 = \$2.00

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 20 students

#8 Analyze the Units 3.OA.A.3

Each of the 20 students costs $2.00, so multiply $2.00 by 20 to get the total.

\$2.00 \times 20 = \$40.00

Equal groups of money means repeated addition, which is multiplication.

Answer: $40.00

4 · Reviewdoes it hold up?

Each student costs about $2, and $2 times 20 is about $40. Our exact answer $40.00 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 20 erasers cost $\$0.95 \times 20 = \$19.00$ and 20 pairs of scissors cost $\$1.05 \times 20 = \$21.00$ ; their sum is $40.00.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 4 easy

One eraser costs $\$0.85$ and one pair of scissors costs $\$0.90$ . The teacher wants to give every one of the $24$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 24 students gets one eraser ($0.85) and one pair of scissors ($0.90). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.85.
One pair of scissors costs $0.90.
There are 24 students, each getting one of each item.

Unknowns

The total money needed to buy 24 erasers and 24 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 24. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.85 + \$0.90 = \$1.75

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 24 students

#8 Analyze the Units 3.OA.A.3

Each of the 24 students costs $1.75, so multiply $1.75 by 24 to get the total.

\$1.75 \times 24 = \$42.00

Equal groups of money means repeated addition, which is multiplication.

Answer: $42.00

4 · Reviewdoes it hold up?

Each student costs about $2, and $2 times 24 is about $48. Our exact answer $42.00 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 24 erasers cost $\$0.85 \times 24 = \$20.40$ and 24 pairs of scissors cost $\$0.90 \times 24 = \$21.60$ ; their sum is $42.00.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 5 medium

One eraser costs $\$0.60$ and one pair of scissors costs $\$0.65$ . The teacher wants to give every one of the $25$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 25 students gets one eraser ($0.60) and one pair of scissors ($0.65). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.60.
One pair of scissors costs $0.65.
There are 25 students, each getting one of each item.

Unknowns

The total money needed to buy 25 erasers and 25 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 25. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.60 + \$0.65 = \$1.25

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 25 students

#8 Analyze the Units 3.OA.A.3

Each of the 25 students costs $1.25, so multiply $1.25 by 25 to get the total.

\$1.25 \times 25 = \$31.25

Equal groups of money means repeated addition, which is multiplication.

Answer: $31.25

4 · Reviewdoes it hold up?

Each student costs about $2, and $2 times 25 is about $50. Our exact answer $31.25 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 25 erasers cost $\$0.60 \times 25 = \$15.00$ and 25 pairs of scissors cost $\$0.65 \times 25 = \$16.25$ ; their sum is $31.25.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 6 medium

One eraser costs $\$1.10$ and one pair of scissors costs $\$0.90$ . The teacher wants to give every one of the $28$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 28 students gets one eraser ($1.10) and one pair of scissors ($0.90). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $1.10.
One pair of scissors costs $0.90.
There are 28 students, each getting one of each item.

Unknowns

The total money needed to buy 28 erasers and 28 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 28. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$1.10 + \$0.90 = \$2.00

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 28 students

#8 Analyze the Units 3.OA.A.3

Each of the 28 students costs $2.00, so multiply $2.00 by 28 to get the total.

\$2.00 \times 28 = \$56.00

Equal groups of money means repeated addition, which is multiplication.

Answer: $56.00

4 · Reviewdoes it hold up?

Each student costs about $2, and $2 times 28 is about $56. Our exact answer $56.00 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 28 erasers cost $\$1.10 \times 28 = \$30.80$ and 28 pairs of scissors cost $\$0.90 \times 28 = \$25.20$ ; their sum is $56.00.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 7 medium

One eraser costs $\$0.40$ and one pair of scissors costs $\$0.55$ . The teacher wants to give every one of the $30$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 30 students gets one eraser ($0.40) and one pair of scissors ($0.55). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.40.
One pair of scissors costs $0.55.
There are 30 students, each getting one of each item.

Unknowns

The total money needed to buy 30 erasers and 30 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 30. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.40 + \$0.55 = \$0.95

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 30 students

#8 Analyze the Units 3.OA.A.3

Each of the 30 students costs $0.95, so multiply $0.95 by 30 to get the total.

\$0.95 \times 30 = \$28.50

Equal groups of money means repeated addition, which is multiplication.

Answer: $28.50

4 · Reviewdoes it hold up?

Each student costs about $1, and $1 times 30 is about $30. Our exact answer $28.50 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 30 erasers cost $\$0.40 \times 30 = \$12.00$ and 30 pairs of scissors cost $\$0.55 \times 30 = \$16.50$ ; their sum is $28.50.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 8 medium

One eraser costs $\$0.90$ and one pair of scissors costs $\$0.95$ . The teacher wants to give every one of the $30$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 30 students gets one eraser ($0.90) and one pair of scissors ($0.95). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.90.
One pair of scissors costs $0.95.
There are 30 students, each getting one of each item.

Unknowns

The total money needed to buy 30 erasers and 30 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 30. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.90 + \$0.95 = \$1.85

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 30 students

#8 Analyze the Units 3.OA.A.3

Each of the 30 students costs $1.85, so multiply $1.85 by 30 to get the total.

\$1.85 \times 30 = \$55.50

Equal groups of money means repeated addition, which is multiplication.

Answer: $55.50

4 · Reviewdoes it hold up?

Each student costs about $2, and $2 times 30 is about $60. Our exact answer $55.50 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 30 erasers cost $\$0.90 \times 30 = \$27.00$ and 30 pairs of scissors cost $\$0.95 \times 30 = \$28.50$ ; their sum is $55.50.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 9 hard

One eraser costs $\$0.25$ and one pair of scissors costs $\$0.75$ . The teacher wants to give every one of the $32$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 32 students gets one eraser ($0.25) and one pair of scissors ($0.75). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.25.
One pair of scissors costs $0.75.
There are 32 students, each getting one of each item.

Unknowns

The total money needed to buy 32 erasers and 32 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 32. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.25 + \$0.75 = \$1.00

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 32 students

#8 Analyze the Units 3.OA.A.3

Each of the 32 students costs $1.00, so multiply $1.00 by 32 to get the total.

\$1.00 \times 32 = \$32.00

Equal groups of money means repeated addition, which is multiplication.

Answer: $32.00

4 · Reviewdoes it hold up?

Each student costs about $1, and $1 times 32 is about $32. Our exact answer $32.00 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 32 erasers cost $\$0.25 \times 32 = \$8.00$ and 32 pairs of scissors cost $\$0.75 \times 32 = \$24.00$ ; their sum is $32.00.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 10 hard

One eraser costs $\$0.70$ and one pair of scissors costs $\$0.80$ . The teacher wants to give every one of the $35$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 35 students gets one eraser ($0.70) and one pair of scissors ($0.80). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.70.
One pair of scissors costs $0.80.
There are 35 students, each getting one of each item.

Unknowns

The total money needed to buy 35 erasers and 35 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 35. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.70 + \$0.80 = \$1.50

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 35 students

#8 Analyze the Units 3.OA.A.3

Each of the 35 students costs $1.50, so multiply $1.50 by 35 to get the total.

\$1.50 \times 35 = \$52.50

Equal groups of money means repeated addition, which is multiplication.

Answer: $52.50

4 · Reviewdoes it hold up?

Each student costs about $2, and $2 times 35 is about $70. Our exact answer $52.50 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 35 erasers cost $\$0.70 \times 35 = \$24.50$ and 35 pairs of scissors cost $\$0.80 \times 35 = \$28.00$ ; their sum is $52.50.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 11 hard

One eraser costs $\$0.50$ and one pair of scissors costs $\$0.45$ . The teacher wants to give every one of the $40$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 40 students gets one eraser ($0.50) and one pair of scissors ($0.45). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.50.
One pair of scissors costs $0.45.
There are 40 students, each getting one of each item.

Unknowns

The total money needed to buy 40 erasers and 40 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 40. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.50 + \$0.45 = \$0.95

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 40 students

#8 Analyze the Units 3.OA.A.3

Each of the 40 students costs $0.95, so multiply $0.95 by 40 to get the total.

\$0.95 \times 40 = \$38.00

Equal groups of money means repeated addition, which is multiplication.

Answer: $38.00

4 · Reviewdoes it hold up?

Each student costs about $1, and $1 times 40 is about $40. Our exact answer $38.00 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 40 erasers cost $\$0.50 \times 40 = \$20.00$ and 40 pairs of scissors cost $\$0.45 \times 40 = \$18.00$ ; their sum is $38.00.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Variant 12 hard

One eraser costs $\$0.35$ and one pair of scissors costs $\$0.65$ . The teacher wants to give every one of the $50$ students in Mia's class one eraser and one pair of scissors. How much money is needed in all to buy the erasers and the scissors?

Your answer

Show solution

1 · Understandwhat's really being asked

Each of 50 students gets one eraser ($0.35) and one pair of scissors ($0.65). Find the total cost for all the erasers and all the scissors together.

Givens

One eraser costs $0.35.
One pair of scissors costs $0.65.
There are 50 students, each getting one of each item.

Unknowns

The total money needed to buy 50 erasers and 50 pairs of scissors.

Constraints

Every student receives exactly one eraser and one pair of scissors.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #8 Analyze the Units

Each student's cost is one small subproblem (eraser + scissors). Find the cost for one student, then multiply by 50. Tracking dollars keeps the arithmetic honest.

3 · Execute2 carry out the plan

1Cost for one student

#7 Identify Subproblems 3.NBT.A.2

Add the price of one eraser and one pair of scissors to get the cost of supplies for a single student.

\$0.35 + \$0.65 = \$1.00

Combining two prices is just adding money amounts, a Grade 3 addition skill.

2Cost for all 50 students

#8 Analyze the Units 3.OA.A.3

Each of the 50 students costs $1.00, so multiply $1.00 by 50 to get the total.

\$1.00 \times 50 = \$50.00

Equal groups of money means repeated addition, which is multiplication.

Answer: $50.00

4 · Reviewdoes it hold up?

Each student costs about $1, and $1 times 50 is about $50. Our exact answer $50.00 is close to that estimate, so it is reasonable.

Another way: Compute the two totals separately: 50 erasers cost $\$0.35 \times 50 = \$17.50$ and 50 pairs of scissors cost $\$0.65 \times 50 = \$32.50$ ; their sum is $50.00.

Standardsmin grade 3

3.OA.A.3 Solve multiplication and division word problems within 100 — Multiplying the per-student cost by the number of students.
3.NBT.A.2 Fluently add and subtract within 1000 — Adding the eraser and scissors prices for one student.

💡Takeaway. Find what one kid costs, then multiply by how many kids -- that is all Grade 3 thinking!

Where next?

← Back to the problem: Set up an expression and compute in order