No even numbers add up to 9. The sum of even numbers is always an even number.
1-9
-45
288. All multiples of 9 will have digits that add to a multiple of 9. To get a multiple of 9 to be all even, you need to get them to add to 18, since no set of even numbers will add up to 9. 288 is the lowest multiple of 9 to be able to add to 18. ■
92
No even numbers add up to 9. The sum of even numbers is always an even number.
An odd number of odd numbers can not add up to an even number. There fore any 9 (odd) odd numbers can not add up to 50 (even).
9 9
1-9
9 and 9
99
8 + 9 = 17
81
16 and 9
16
-45
288. All multiples of 9 will have digits that add to a multiple of 9. To get a multiple of 9 to be all even, you need to get them to add to 18, since no set of even numbers will add up to 9. 288 is the lowest multiple of 9 to be able to add to 18. ■