Question

The common factors of $9,15$ and $21$ are ………………… and ………………….. .

Answer 1

The common factors are the factors which are common between the given numbers.

Since factors of $9=1,3,9$

Factors of $15=1,3,5,15$

Factors of $21=1,3,7,21$

Hence, common factors of $9,15$ and $21$ are $1$ and $3$.