For this, you want to find the Factors, the Common ones and then the Greatest of those.
*Always list factor in pairs so that none are missed/left out
First, Factors of 32
1, 32
2, 16
4, 8
Now, Factors of 81
1, 81
3, 27
9
The next step is to highlight/circle the common factors
1,
As there is only one common factor, that is the greatest.
The GCF is 1
