Question

HCF of 168 and 126 is:

• A. 21
• B. 42
• C. 14
• D. 18

Answer 1

The correct option is B

42

Step 1: Find the prime factors of 168 and 126

$168=2\times 2\times 2\times 3\times 7$

$126=2\times 3\times 3\times 7$

Step 2: Finding the HCF

To find the HCF, find the product of all common factors of 168 and 126 as follows:

$\begin{array}{rcl}\mathrm{HCF}& =& 2\times 3\times 7\\ & =& 42\end{array}$

Final Answer: Hence, option B is correct.