Question

Find the prime factors of the following numbers:

(4) 420

Answer 1

The prime factorisation of the number 420 by successive division method is given as follows:
$\begin{array}{cc}2& 420\\ 2& 210\\ 3& 105\\ 5& 35\\ 7& 7\\ & 1\end{array}$
⇒ 420 = 2 × 2 × 3 × 5 × 7

Thus, the prime factors are 2, 3, 5 and 7.