This is known as multiplying by the reciprocal. The sum then becomes multiplying two fractions, which is done using the method above. This fraction can be simplified by dividing common factors.

If we can't multiply by a big number like 22 in our heads, then we split the bottom number up into its ones, tens and hundreds, multiplying the top number by each column of the bottom numbers ...

Ken Shirriff] has been sharing a really low-level look at Intel’s Pentium (1993) processor. The Pentium’s architecture was highly innovative in many ways, and one of [Ken]’s ...