Question

Use the divisibility tests to determine whether the following numbers are divisible by 2, 3, 4, 5, 6, 9 or 11.

(2) 135

Answer 1

We can observe that the sum of the digits 1, 3 and 5 is 9, which is divisible by both 3 and 9.
If the sum of all the digits in a number is divisible by 3 and 9, then the number is divisible by both 3 and 9. So, the number 135 is divisible by 3 and 9.

Also, the number 135 has digit 5 in its units place.
We know that if a number has either 0 or 5 in its units place, then the number is divisible by 5. So, the number 135 is divisible by 5.

Hence, the number 135 is divisible by 3, 5 and 9.