are 1, 7.
The way to calculate the factors of 7 is as follows. The first two factors - and sometimes the only two - are the number itself, and 1.
Try 1. 1 x 7 = 7, so put these into our factor list.
1 ... 7
Take 2... no good. 7/2 isn't a whole number. So we skip 2.
Now take 3... no. 7/3 isn't a whole number. So we skip 3.
Now, since we don't have any more numbers to try, we're done!
