Question

Which of these numbers: 3, 4, 18, 111, 123, 340, 345, 456, 555 ... Are multiples of 3, but not multiples of 9? ​

Answer 1

Numbers 3, 111, 123, 345, 456 and 555 are multiples of 3 but not 9.
Divisibility rule of 3 = The sum of digits should be divisible by 3

Example : 123 / 3 = (1 + 2 + 3) / 3 = 6/3
Therefore 123 is divisible by 3 because 6 is divisible by 3

Divisibility rule of 9 = Sum of digits should be divisible by 9

Example 135 / 9 = (1 + 3 + 5) / 9 = 9 / 9
Therefore 135 is divisible by 9 because 9 is divisible by 9

Hope this helps

Answer 2

555,3, 111, 123, 345, 456