Answer :

It's 3. 3 can divide into all those numbers evenly and be the one with the smallest value

gabby5792
It would be 3 !

Find all the factors of 3, 9 , and 12 and see that one that are alike FIRST

Factors :

Factors of 3
3, 6, 9, 12, 15, 18

Factors of 9
9, 18, 27, 36, 45, 54

Factors of 12
12, 24, 36, 48, 60

They can all divide by 3 making 3 the greatest common factor