Question

Which of the following is prime factorisation of 28?

• A. $2\times 3\times 4\times 7$
• B. $2\times 2\times 7$
• C. $2\times 4\times 7$
• D. $2\times 14$

Answer 1

The correct option is B $2\times 2\times 7$

The prime factorisation of a number is to find all the prime factors which multiply together to form the number.

$\begin{array}{cc}2& 28\\ 2& 14\\ 7& 7\\ & 1\end{array}$

$\therefore$ The prime factorisation of 28
​​​​​​​ = 2 × 2 × 7