Maths

Find the numbers which divide $a$.

Now, the numbers which divide $a$ are called factors of $a$.

Take another number $b$.

Find the factors of $b$.

Now, factors which appear both in $a$ and $b$ are called common factors.

Factors of a prime number are $1$ and itself.

For eg:-

$6=2×3$ and $4=2×2$

So, common factors of $6$ and $4$ is $2$.

Factors of $11$ are $1$ and $11$.

The factors of $12$ are $1,2,3,4,6,12$ or $12=1×2×2×3$

The factors of $15$ are $1,3,5,15$ or $15=1×3×5$

The common factors are $1$ and $3$.