Question

Find the greatest number that divides 12 and 40 exactly.

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is D 4

A number that divides 12 and 40 exactly is a common factor of 12 and 40.

$\therefore$ The greatest number that divides 12 and 40 is equal to their Highest Common Factor (HCF).

We need to find the HCF of 12 and 40.

Factors of 12 = 1, 2, 3, 4, 6, 12
Factors of 40 = 1 , 2 , 4, 5, 8, 10, 20, 40

The common factors of 12 and 40 are 1, 2 and 4.

$\therefore$ The highest common factor of 12 and 40 is 4.
$\therefore$The greatest number that divides 12 and 40 exactly is 4.