Question

Which of the following is not a factor of 78?
.

• A. 13
• B. 36
• C. 39

Answer 1

The correct option is B 36

Any number that divides 78 with the remainder as $0$ is a factor of 78.
78 can be expressed as:
$78=1\times 78$
$78=2\times 39$
$78=3\times 26$
$78=6\times 13$

As 36 does not appear when 78 is expressed as a product of two numbers, it does not divide 78 evenly.

Hence, 36 isn't a factor of 78.