text: 3 1/4 - 1 3/4 what do i do if my top numerator is less than my bottom numerator?   you could convert the whole thing to improper fractions, so 3 1/4 would be 13/4 and 1 3/4 would be 7/4. 13/4-7/4=6/4.  6/4 can be reduced to 3/2 which, converted to a mixed number, is 1 1/2.