Question

find the sum of the common prime factor of 168 and 252.

Answer 1

the common prime factor is 2,4,8.

Answer 2

$168 \: = {2}^{3} \times 3 \times 7 \\ 252 \: = {2}^{2} \times {3}^{2} \times 7 \\ common \: prime \: factors \: are \\ 2 \: \: \: 3 \: \: \: 7 \\ sum \: of \: prime \: factors \: = 2 + 3 + 7 = 12$