This was explained the other day. The IOF's number are 100% correct to them, because all male Palestinians aged 18-50 are considered hamas.
So now look at the numbers: 33k dead, 13k 'hamas' and 20k women, kids, and old men.
your source on 33k, and the amount of women and children killed, is hamas. that's why you're confused about how the math can work......