Question

Which is the highest common factor of 15 and 27?

• A. 3
• B. 9
• C. 5
• D. 1

Answer 1

The correct option is A 3

15 can be written as:

$15=1\times 15$
$15=3\times 5$

$\therefore$The factors of 15 are 1, 3, 5, and 15.

27 can be written as:

$27=1\times 27$
$27=3\times 9$

$\therefore$ The factors of 27 are 1, 3, 9 and 27.

The common factors of 15 and 27 are 1 and 3.

Hence, the highest common factor of 15 and 27 is 3.