 If one of and is odd, the other is odd too; this means that the fractions, if any, will cancel out, and discarding the remainders does not introduce any error.Below is a lookup table of quarter squares with the remainder discarded for the digits 0 through 18; this allows for the multiplication of numbers up to .If, for example, you wanted to multiply 9 by 3, you observe that the sum and difference are 12 and 6 respectively.