Question

what are the prime factors of 42?
a 2, 3, 7
b 2, 3, 7, 42
c 1, 2, 3, 7
d 1, 42

Explanation:

Step1: Divide 42 by smallest prime

$42 \div 2 = 21$

Step2: Divide 21 by next prime

$21 \div 3 = 7$

Step3: 7 is a prime number

Stop division here.

Step4: Identify valid prime factors

Prime factors are primes that divide 42, so exclude non-primes (1, 42).

Answer:

A. 2, 3, 7