Question

The common factors of 15 and 60 are _____.

• A. 1, 2, 3, 9 and 15
• B. 1, 3, 9 and 15
• C. 1, 3, 5 and 15
• D. 1, 5, 10 and 15

Answer 1

The correct option is C 1, 3, 5 and 15

15 and 60 can be written in the following different ways.

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

$60=1\times 60$
$60=2\times 30$
$60=3\times 20$
$60=4\times 15$
$60=5\times 12$
$60=6\times 10$

$\therefore$Factors of 15 = 1, 3, 5, and 15
Factors of 60 = 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30 and 60

∴ Common factors of 15 and 60 = 1, 3, 5 and 15