Question

Which of the following is a perfect number?

• A. 6
• B. 4
• C. 9
• D. 10

Answer 1

The correct option is A

6

A number is said to be a perfect number if the sum of all of its factors is twice the number.

Factors of 4 are 1, 2 and 4, the sum of its factors is 1+2+4=7 (not a perfect number)

Factors of 6 are 1, 2, 3 and 6, the sum of its factors is 1+2+3+6=12 (a perfect number)

Factors of 9 are 1, 3 and 9, the sum of its factors is 1+3+9=13 (not a perfect number)

Factors of 10 are 1, 2, 5 and 10, the sum of its factors is 1+2+5+10=18 (not a perfect number)