Representative Problem

From 5 number cards, choose 3 different cards to form the largest possible three-digit number. Then rotate that number $180\degree$ clockwise (turn all three digits at once, as one block) to read a new number, and find the difference between the original number and the rotated number.

Number cards: $8$, $5$, $9$, $1$, $0$

When a card is turned $180\degree$, each digit looks like another digit: $0 \to 0$, $1 \to 1$, $8 \to 8$, $9 \to 6$, $5 \to 2$. Remember the whole number is flipped at once, so the order of the digits also reverses.

• The largest three-digit number you can make is [ ].
• Rotating that number $180\degree$ clockwise gives [ ].
• Therefore the difference of the two numbers is [ ] $-$ [ ] $=$ [ ].