Multiplying 2 x 2 is easy. But multiplying two numbers with more than a billion digits each — that takes some serious computation. The multiplication technique taught in grade school may be ...

Activity: Multiplying 2-digits by 1-digit Complete this interactive activity to better understand how to multiply a 2-digit number by a 1-digit number. Then put your knowledge to the test.

We'll explore how this shortcut works for both two-digit numbers multiplied by themselves, and even for multiplying two different numbers ending in 5.

The most efficient way to multiply two large numbers is often far from obvious.