They are all 3-digit numbers, so I'm going to put three lines to represent the three digits in the number.
___ ___ ___
The first digit has five possible options: 5, 6, 7, 8, 9
The second digit has two possible options: 3, 4
The third digit uses the remaining number from the second space: either 3 or 4;;; 1 option
_5_ _2_ _1_
We multiply these together to get 5 * 2 * 1 which is equal to 10 numbers
(if you want, you can list them out as well. they are 534 543 634 643 734 743 834 843 934 943)
- h
