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 ...

Ah, math. It’s why I became an English major. But now math is spinning back around and haunting me in the form of my fifth grader. Last night, I found myself dealing with how to multiply fractions as ...

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 ...

We’ve often noted that whether had ancient man known binary, we could all count to 1023 on our fingers. We thought about that while watching [Numberphile’s] latest video about “Russian” multiplication ...

This summer, battle lines were drawn over a simple math problem: 8 ÷ 2(2 + 2) = ? If you divide 8 by 2 first, you get 16, but if you multiply 2 by (2 + 2) first, you get 1. So, which answer is right?