The digital sum of multiples of 9 always add up to 9 as for example 9*9 = 81 and 8+1 = 9
If they are multiples of 9, the digits add up to a multiple of 9.
There are infinitely many multiples of 9 and it is not possible to add them all.
That the sum of its digits add up to 9 as for example 9*9 = 81 and 8+1 = 9
If you add up the two digits and they make either 3, 6, or 9
All digits will add up to 9 when one keeps adding until he/she gets a single digit.
117. All multiples of 9 have digits that add up to something divisible by 9. Examples, 117, 36, 45, 54 all have digits that add up to 9.
The digits of 498 do not add to a multiple of 9 so it isn't.
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. ■
12 lots of 3 add up to 36
All multiples of 3 have digits that add up to a multiple of 3.