Question

Which of the following numbers do not have exactly 6 factors?

• A. 20
• B. 12
• C. 18
• D. 24

Answer 1

The correct option is D 24

$20=2\times 2\times 5$
2 x 2 = 4 has 3 factors 1, 2 and 4
5 has two factors 1 and 5
Total factors of 20 = 3 x 2 = 6

$12=2\times 2\times 3$
2 x 2 = 4 has 3 factors 1, 2 and 4
3 has two factors 1 and 3
Total factors of 12 = 3 x 2 = 6

$18=2\times 3\times 3$
2 has two factors 1 and 2
3 x 3 = 9 has 3 factors 1, 3 and 9
Total factors of 18 = 3 x 2 = 6

$24=2\times 2\times 2\times 3$
2 x 2 x 2 = 8 has 4 factors 1, 2, 4 and 8
3 has 2 factors 1 and 3
Total factors of 24 = 4 x 2 = 8

So, The number which do not have exactly 6 factors = 24