Mathematicians love a good puzzle. Even something as abstract as multiplying matrices (two-dimensional tables of numbers) can feel like a game when you try to find the most efficient way to do it.

Multiply by 5 using the grouping of objects, counting by fives, and arrays. Explore the Multiply by 5 facts using the grouping of objects, counting by fives, and arrays. Compete against characters to ...

Numberphile revived an ancient multiplication trick—halves and doubles—also called Egyptian or Russian math, where you repeatedly halve one number and double the other. After crossing out rows with ...

A recent paper set the fastest record for multiplying two matrices. But it also marks the end of the line for a method researchers have relied on for decades to make improvements. For computer ...