Question

Determine if 17250 is divisible by 15.

(Hint: 3 and 5 are co-prime numbers. Test the divisibility of the number by 3 and 5)​

Answer 1

Answer:

The prime factorization of 45 = 5 x 9

25110 is divisible by 5 as 0 is at its unit place

25110 is divisible by 9 as sum of digits is divisible by 9.

Therefore, the number must be divisible by 5 x 9 =45

Answer 2

The divisibility test of 3 is adding all digits.

• If the sum is not divisible by 3, it is not a multiple.

The divisibility test of 5 is finding the last digit.

• It should end with either 0 or 5.

So 17250 is a multiple of 5.

1+7+2+5+0=15, which is a multiple of 3.

So 17250 is a multiple of 3.

So 17250 should be a multiple of 15.