The factors of 128 are 1, 2, 4, 8, 16, 32, 64, 128. This is how to find the factors of 128. Take 128 and the number 1. Those are the first two factors.
Try 1. 1 x 128 = 128, so put these into our factor list.
1
...
128
Take 2. 2 x 64 = 128, which means we add these to our factor list.
1
2
...
64
128
Now take 3... no. 128/3 isn't a whole number. So we skip 3.
Next try 4. 4 x 32 = 128, so we add these to our list of factors.
1
2
4
...
32
64
128
Now try 5... nope! 128/5 isn't a whole number. So we skip 5.
Try 6... no good. 128/6 isn't a whole number. So we skip 6.
Take 7... no. 128/7 isn't a whole number. So we skip 7.
Now take 8. 8 x 16 = 128, so we add these to our list of factors.
1
2
4
8
...
16
32
64
128
Next try 9... nope! 128/9 isn't a whole number. So we skip 9.
Now try 10... no good. 128/10 isn't a whole number. So we skip 10.
Try 11... no. 128/11 isn't a whole number. So we skip 11.
Now, since we don't have any more numbers to try, we're done!