Question

By which of the following numbers is 672 divisible?

• A. 7
• B. 9
• C. 10
• D. 5

Answer 1

The correct option is A 7

To check divisibility by 7, we find 2a + 3b + c

So, for 672
a = 6, b = 7 and c = 2
$2\times 6$ + $3\times 7$ + 2 = 12 + 21 + 2 = 35
35 is divisible by 7
$\therefore$ 672 is divisible by 7.

672 is not divisible by 9 because the sum 6 + 7 + 2 = 15 is not divisible 9.

672 is not divisible by 5 and 10 because it does not have a 0 or 5 in its ones place.