Question

Which of the following number should be multiplied by 35 to make a number divisible by 15 ?

• A. 2
• B. 3
• C. 4
• D. 7

Answer 1

The correct option is B 3

The number is divisible by 15, if it divisible by 3 and 5

When 35 is multiplied by 2
35 × 2 = 70
70 is not divisible by 3
70 is divisible by 5
Although 70 is divisible by 5, it is not divisible by 3, so it is not divisible by 15

When 35 is multiplied by 3
35 × 3 = 105
105 is divisible by 3
105 is divisible by 5
105 is divisible by both 3 and 5,so it is divisible by 15

When 35 is multiplied by 4
35 × 4 = 140
140 is not divisible by 3
140 is divisible by 5
Although 140 is divisible by 5, it is not divisible by 3, so it is not divisible by 15

When 35 is multiplied by 7
35 × 7 = 245
245 is not divisible by 3
245 is divisible by 5
Although 245 is divisible by 5, it is not divisible by 3, so it is not divisible by 15

Thus, when 35 is multiplied by 3, it results in 105 which is divisible by both 3 and 5, so 105 is divisible by 15