Divide 84 by the smallest prime number (2):
84 ÷ 2 = 42
Divide 42 by 2 again:
42 ÷ 2 = 21
Divide 21 by the next smallest prime number (3):
21 ÷ 3 = 7
7 is already a prime number.
So, 84 = 2 × 2 × 3 × 7 or 84 = 2² × 3 × 7.
Prime factors of 84 are 2² × 3 × 7.