Remove the largest common factor

I think you mean the greatest common factor to factor
this is useful because say you want to divide 100 by 1000 then the common factor is 100 so factor that out and get 1/10

so just find the factors or the whole numbers that multiply to get those numbers exg
factors of 18=2*3*3
note:2*3 means 2 times 3
so just find the factors and group the common ones exg
896 and 322
factor
896=2*2*2*2*2*2*2*7
644=2*2*7*23
we see that 2*2*7 is common to both so the greatest common factor is 2*2*7=28