Practice · Find a future date using days per month · Sensim Math

Variant 1 medium

March has 31 days. Starting from March 25, 2025, what is the date 45 days later? Give the month and day.

(A knuckle mnemonic: months on the raised knuckles have 31 days; months in the dips between knuckles have 30 days. February is the short month.)

Your answer (check it yourself)

Show solution

1 · Understandwhat's really being asked

March has 31 days. Starting from March 25, 2025, find the date that is 45 days later (give month and day).

Givens

March has 31 days.
Start date is March 25, 2025.
We move forward 45 days.
The knuckle mnemonic in the figure tells which months have 30 or 31 days.

Unknowns

The month and day that is 45 days after March 25, 2025.

Constraints

Days roll over into the next month once a month's days run out.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #11 Work Backwards

Break the days into 'days left in the start month' plus 'days spilling into later months.' Subtract the start-month part, and count the rest forward using each month's day count. This keeps every month boundary clear.

3 · Execute3 carry out the plan

1Count the days left in March

#7 Identify Subproblems 1.MD.B.3

From March 25 to the end of March (March 31) is 31 minus 25 days.

31 - 25 = 6

March 25 plus 6 days lands exactly on the last day of March.

2Find how many days reach into the next month(s)

#7 Identify Subproblems 1.MD.B.3

Of the 45 days, 6 are used getting to the end of March. The remaining days fall into the following month(s).

45 - 6 = 39

After landing on the last day of the start month, the leftover days are counted forward into the next month.

3Count forward into the next month(s)

#11 Work Backwards 1.MD.B.3

Stepping the leftover 39 days forward from the last day of March, using each month's true length, lands on May 9.

\text{end of }March + 39\text{ days} = \text{May 9}

Days roll into the next month once a month's days run out; keep going until the leftover days are used up.

Answer: May 9

4 · Reviewdoes it hold up?

Counting forward 45 days from March 25, 2025, using each month's true length, lands on May 9, which is a valid date in its month.

Another way: Count by whole months: fill the start month to its last day, then add the remaining days month by month until the leftover runs out — same answer.

Standardsmin grade 1

1.MD.B.3 Tell and write time in hours and half-hours using analog and digital clocks — Working with calendar dates and days within months to find a future date.

💡Takeaway. Use up the days left this month first, then count the rest into the next month: simple Grade 1 calendar counting!

Variant 2 medium

June has 30 days. Starting from June 12, 2024, what is the date 25 days later? Give the month and day.

(A knuckle mnemonic: months on the raised knuckles have 31 days; months in the dips between knuckles have 30 days. February is the short month.)

Your answer (check it yourself)

Show solution

1 · Understandwhat's really being asked

June has 30 days. Starting from June 12, 2024, find the date that is 25 days later (give month and day).

Givens

June has 30 days.
Start date is June 12, 2024.
We move forward 25 days.
The knuckle mnemonic in the figure tells which months have 30 or 31 days.

Unknowns

The month and day that is 25 days after June 12, 2024.

Constraints

Days roll over into the next month once a month's days run out.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #11 Work Backwards

Break the days into 'days left in the start month' plus 'days spilling into later months.' Subtract the start-month part, and count the rest forward using each month's day count. This keeps every month boundary clear.

3 · Execute3 carry out the plan

1Count the days left in June

#7 Identify Subproblems 1.MD.B.3

From June 12 to the end of June (June 30) is 30 minus 12 days.

30 - 12 = 18

June 12 plus 18 days lands exactly on the last day of June.

2Find how many days reach into the next month(s)

#7 Identify Subproblems 1.MD.B.3

Of the 25 days, 18 are used getting to the end of June. The remaining days fall into the following month(s).

25 - 18 = 7

After landing on the last day of the start month, the leftover days are counted forward into the next month.

3Count forward into the next month(s)

#11 Work Backwards 1.MD.B.3

Stepping the leftover 7 days forward from the last day of June, using each month's true length, lands on July 7.

\text{end of }June + 7\text{ days} = \text{July 7}

Days roll into the next month once a month's days run out; keep going until the leftover days are used up.

Answer: July 7

4 · Reviewdoes it hold up?

Counting forward 25 days from June 12, 2024, using each month's true length, lands on July 7, which is a valid date in its month.

Another way: Count by whole months: fill the start month to its last day, then add the remaining days month by month until the leftover runs out — same answer.

Standardsmin grade 1

1.MD.B.3 Tell and write time in hours and half-hours using analog and digital clocks — Working with calendar dates and days within months to find a future date.

💡Takeaway. Use up the days left this month first, then count the rest into the next month: simple Grade 1 calendar counting!

Variant 3 medium

December has 31 days. Starting from December 20, 2024, what is the date 35 days later? Give the month and day.

(A knuckle mnemonic: months on the raised knuckles have 31 days; months in the dips between knuckles have 30 days. February is the short month.)

Your answer (check it yourself)

Show solution

1 · Understandwhat's really being asked

December has 31 days. Starting from December 20, 2024, find the date that is 35 days later (give month and day).

Givens

December has 31 days.
Start date is December 20, 2024.
We move forward 35 days.
The knuckle mnemonic in the figure tells which months have 30 or 31 days.

Unknowns

The month and day that is 35 days after December 20, 2024.

Constraints

Days roll over into the next month once a month's days run out.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #11 Work Backwards

Break the days into 'days left in the start month' plus 'days spilling into later months.' Subtract the start-month part, and count the rest forward using each month's day count. This keeps every month boundary clear.

3 · Execute3 carry out the plan

1Count the days left in December

#7 Identify Subproblems 1.MD.B.3

From December 20 to the end of December (December 31) is 31 minus 20 days.

31 - 20 = 11

December 20 plus 11 days lands exactly on the last day of December.

2Find how many days reach into the next month(s)

#7 Identify Subproblems 1.MD.B.3

Of the 35 days, 11 are used getting to the end of December. The remaining days fall into the following month(s).

35 - 11 = 24

After landing on the last day of the start month, the leftover days are counted forward into the next month.

3Count forward into the next month(s)

#11 Work Backwards 1.MD.B.3

Stepping the leftover 24 days forward from the last day of December, using each month's true length, lands on January 24.

\text{end of }December + 24\text{ days} = \text{January 24}

Days roll into the next month once a month's days run out; keep going until the leftover days are used up.

Answer: January 24

4 · Reviewdoes it hold up?

Counting forward 35 days from December 20, 2024, using each month's true length, lands on January 24, which is a valid date in its month.

Another way: Count by whole months: fill the start month to its last day, then add the remaining days month by month until the leftover runs out — same answer.

Standardsmin grade 1

1.MD.B.3 Tell and write time in hours and half-hours using analog and digital clocks — Working with calendar dates and days within months to find a future date.

💡Takeaway. Use up the days left this month first, then count the rest into the next month: simple Grade 1 calendar counting!

Variant 4 medium

November has 30 days. Starting from November 5, 2025, what is the date 60 days later? Give the month and day.

(A knuckle mnemonic: months on the raised knuckles have 31 days; months in the dips between knuckles have 30 days. February is the short month.)

Your answer (check it yourself)

Show solution

1 · Understandwhat's really being asked

November has 30 days. Starting from November 5, 2025, find the date that is 60 days later (give month and day).

Givens

November has 30 days.
Start date is November 5, 2025.
We move forward 60 days.
The knuckle mnemonic in the figure tells which months have 30 or 31 days.

Unknowns

The month and day that is 60 days after November 5, 2025.

Constraints

Days roll over into the next month once a month's days run out.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #11 Work Backwards

Break the days into 'days left in the start month' plus 'days spilling into later months.' Subtract the start-month part, and count the rest forward using each month's day count. This keeps every month boundary clear.

3 · Execute3 carry out the plan

1Count the days left in November

#7 Identify Subproblems 1.MD.B.3

From November 5 to the end of November (November 30) is 30 minus 5 days.

30 - 5 = 25

November 5 plus 25 days lands exactly on the last day of November.

2Find how many days reach into the next month(s)

#7 Identify Subproblems 1.MD.B.3

Of the 60 days, 25 are used getting to the end of November. The remaining days fall into the following month(s).

60 - 25 = 35

After landing on the last day of the start month, the leftover days are counted forward into the next month.

3Count forward into the next month(s)

#11 Work Backwards 1.MD.B.3

Stepping the leftover 35 days forward from the last day of November, using each month's true length, lands on January 4.

\text{end of }November + 35\text{ days} = \text{January 4}

Days roll into the next month once a month's days run out; keep going until the leftover days are used up.

Answer: January 4

4 · Reviewdoes it hold up?

Counting forward 60 days from November 5, 2025, using each month's true length, lands on January 4, which is a valid date in its month.

Another way: Count by whole months: fill the start month to its last day, then add the remaining days month by month until the leftover runs out — same answer.

Standardsmin grade 1

1.MD.B.3 Tell and write time in hours and half-hours using analog and digital clocks — Working with calendar dates and days within months to find a future date.

💡Takeaway. Use up the days left this month first, then count the rest into the next month: simple Grade 1 calendar counting!

Variant 5 medium

August has 31 days. Starting from August 8, 2025, what is the date 90 days later? Give the month and day.

(A knuckle mnemonic: months on the raised knuckles have 31 days; months in the dips between knuckles have 30 days. February is the short month.)

Your answer (check it yourself)

Show solution

1 · Understandwhat's really being asked

August has 31 days. Starting from August 8, 2025, find the date that is 90 days later (give month and day).

Givens

August has 31 days.
Start date is August 8, 2025.
We move forward 90 days.
The knuckle mnemonic in the figure tells which months have 30 or 31 days.

Unknowns

The month and day that is 90 days after August 8, 2025.

Constraints

Days roll over into the next month once a month's days run out.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #11 Work Backwards

Break the days into 'days left in the start month' plus 'days spilling into later months.' Subtract the start-month part, and count the rest forward using each month's day count. This keeps every month boundary clear.

3 · Execute3 carry out the plan

1Count the days left in August

#7 Identify Subproblems 1.MD.B.3

From August 8 to the end of August (August 31) is 31 minus 8 days.

31 - 8 = 23

August 8 plus 23 days lands exactly on the last day of August.

2Find how many days reach into the next month(s)

#7 Identify Subproblems 1.MD.B.3

Of the 90 days, 23 are used getting to the end of August. The remaining days fall into the following month(s).

90 - 23 = 67

After landing on the last day of the start month, the leftover days are counted forward into the next month.

3Count forward into the next month(s)

#11 Work Backwards 1.MD.B.3

Stepping the leftover 67 days forward from the last day of August, using each month's true length, lands on November 6.

\text{end of }August + 67\text{ days} = \text{November 6}

Days roll into the next month once a month's days run out; keep going until the leftover days are used up.

Answer: November 6

4 · Reviewdoes it hold up?

Counting forward 90 days from August 8, 2025, using each month's true length, lands on November 6, which is a valid date in its month.

Another way: Count by whole months: fill the start month to its last day, then add the remaining days month by month until the leftover runs out — same answer.

Standardsmin grade 1

1.MD.B.3 Tell and write time in hours and half-hours using analog and digital clocks — Working with calendar dates and days within months to find a future date.

💡Takeaway. Use up the days left this month first, then count the rest into the next month: simple Grade 1 calendar counting!

Variant 6 medium

April has 30 days. Starting from April 10, 2024, what is the date 50 days later? Give the month and day.

(A knuckle mnemonic: months on the raised knuckles have 31 days; months in the dips between knuckles have 30 days. February is the short month.)

Your answer (check it yourself)

Show solution

1 · Understandwhat's really being asked

April has 30 days. Starting from April 10, 2024, find the date that is 50 days later (give month and day).

Givens

April has 30 days.
Start date is April 10, 2024.
We move forward 50 days.
The knuckle mnemonic in the figure tells which months have 30 or 31 days.

Unknowns

The month and day that is 50 days after April 10, 2024.

Constraints

Days roll over into the next month once a month's days run out.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #11 Work Backwards

Break the days into 'days left in the start month' plus 'days spilling into later months.' Subtract the start-month part, and count the rest forward using each month's day count. This keeps every month boundary clear.

3 · Execute3 carry out the plan

1Count the days left in April

#7 Identify Subproblems 1.MD.B.3

From April 10 to the end of April (April 30) is 30 minus 10 days.

30 - 10 = 20

April 10 plus 20 days lands exactly on the last day of April.

2Find how many days reach into the next month(s)

#7 Identify Subproblems 1.MD.B.3

Of the 50 days, 20 are used getting to the end of April. The remaining days fall into the following month(s).

50 - 20 = 30

After landing on the last day of the start month, the leftover days are counted forward into the next month.

3Count forward into the next month(s)

#11 Work Backwards 1.MD.B.3

Stepping the leftover 30 days forward from the last day of April, using each month's true length, lands on May 30.

\text{end of }April + 30\text{ days} = \text{May 30}

Days roll into the next month once a month's days run out; keep going until the leftover days are used up.

Answer: May 30

4 · Reviewdoes it hold up?

Counting forward 50 days from April 10, 2024, using each month's true length, lands on May 30, which is a valid date in its month.

Another way: Count by whole months: fill the start month to its last day, then add the remaining days month by month until the leftover runs out — same answer.

Standardsmin grade 1

1.MD.B.3 Tell and write time in hours and half-hours using analog and digital clocks — Working with calendar dates and days within months to find a future date.

💡Takeaway. Use up the days left this month first, then count the rest into the next month: simple Grade 1 calendar counting!

Variant 7 medium

July has 31 days. Starting from July 20, 2024, what is the date 30 days later? Give the month and day.

(A knuckle mnemonic: months on the raised knuckles have 31 days; months in the dips between knuckles have 30 days. February is the short month.)

Your answer (check it yourself)

Show solution

1 · Understandwhat's really being asked

July has 31 days. Starting from July 20, 2024, find the date that is 30 days later (give month and day).

Givens

July has 31 days.
Start date is July 20, 2024.
We move forward 30 days.
The knuckle mnemonic in the figure tells which months have 30 or 31 days.

Unknowns

The month and day that is 30 days after July 20, 2024.

Constraints

Days roll over into the next month once a month's days run out.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #11 Work Backwards

Break the days into 'days left in the start month' plus 'days spilling into later months.' Subtract the start-month part, and count the rest forward using each month's day count. This keeps every month boundary clear.

3 · Execute3 carry out the plan

1Count the days left in July

#7 Identify Subproblems 1.MD.B.3

From July 20 to the end of July (July 31) is 31 minus 20 days.

31 - 20 = 11

July 20 plus 11 days lands exactly on the last day of July.

2Find how many days reach into the next month(s)

#7 Identify Subproblems 1.MD.B.3

Of the 30 days, 11 are used getting to the end of July. The remaining days fall into the following month(s).

30 - 11 = 19

After landing on the last day of the start month, the leftover days are counted forward into the next month.

3Count forward into the next month(s)

#11 Work Backwards 1.MD.B.3

Stepping the leftover 19 days forward from the last day of July, using each month's true length, lands on August 19.

\text{end of }July + 19\text{ days} = \text{August 19}

Days roll into the next month once a month's days run out; keep going until the leftover days are used up.

Answer: August 19

4 · Reviewdoes it hold up?

Counting forward 30 days from July 20, 2024, using each month's true length, lands on August 19, which is a valid date in its month.

Another way: Count by whole months: fill the start month to its last day, then add the remaining days month by month until the leftover runs out — same answer.

Standardsmin grade 1

1.MD.B.3 Tell and write time in hours and half-hours using analog and digital clocks — Working with calendar dates and days within months to find a future date.

💡Takeaway. Use up the days left this month first, then count the rest into the next month: simple Grade 1 calendar counting!

Variant 8 medium

January has 31 days. Starting from January 15, 2024, what is the date 40 days later? Give the month and day.

(A knuckle mnemonic: months on the raised knuckles have 31 days; months in the dips between knuckles have 30 days. February is the short month.)

Your answer (check it yourself)

Show solution

1 · Understandwhat's really being asked

January has 31 days. Starting from January 15, 2024, find the date that is 40 days later (give month and day).

Givens

January has 31 days.
Start date is January 15, 2024.
We move forward 40 days.
The knuckle mnemonic in the figure tells which months have 30 or 31 days.

Unknowns

The month and day that is 40 days after January 15, 2024.

Constraints

Days roll over into the next month once a month's days run out.

2 · Planchoose the strategy

#7 Identify Subproblems · also uses: #11 Work Backwards

Break the days into 'days left in the start month' plus 'days spilling into later months.' Subtract the start-month part, and count the rest forward using each month's day count. This keeps every month boundary clear.

3 · Execute3 carry out the plan

1Count the days left in January

#7 Identify Subproblems 1.MD.B.3

From January 15 to the end of January (January 31) is 31 minus 15 days.

31 - 15 = 16

January 15 plus 16 days lands exactly on the last day of January.

2Find how many days reach into the next month(s)

#7 Identify Subproblems 1.MD.B.3

Of the 40 days, 16 are used getting to the end of January. The remaining days fall into the following month(s).

40 - 16 = 24

After landing on the last day of the start month, the leftover days are counted forward into the next month.

3Count forward into the next month(s)

#11 Work Backwards 1.MD.B.3

Stepping the leftover 24 days forward from the last day of January, using each month's true length, lands on February 24.

\text{end of }January + 24\text{ days} = \text{February 24}

Days roll into the next month once a month's days run out; keep going until the leftover days are used up.

Answer: February 24

4 · Reviewdoes it hold up?

Counting forward 40 days from January 15, 2024, using each month's true length, lands on February 24, which is a valid date in its month.

Another way: Count by whole months: fill the start month to its last day, then add the remaining days month by month until the leftover runs out — same answer.

Standardsmin grade 1

1.MD.B.3 Tell and write time in hours and half-hours using analog and digital clocks — Working with calendar dates and days within months to find a future date.

💡Takeaway. Use up the days left this month first, then count the rest into the next month: simple Grade 1 calendar counting!

Find a future date using days per month · 8 practice problems

Generated variants — 8

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