Question

Find the Greatest Common Divisor (GCD) of $10$ and $21.$

• A. $2$
• B. $3$
• C. $1$
• D. GCD does not exist.

Answer 1

The correct option is C $1$

We know,
$10=2\times 5$
$\therefore$ Factors of $10$ are $1,2,5$ and $10.$

Also,
$21=3\times 7$
$\therefore$ Factors of $21$ are $1,3,7$ and $21.$

The largest common factor (GCD) is $1.$