This Maths article explains both the mental method and written method for multiplying a 2-digit number by a 1-digit number.

Most everyone learns to multiply the same way. We stack two numbers, multiply every digit in the bottom number by every digit in the top number, and do addition at the end. If you’re multiplying two ...

I think we all remember how demanding multiplication used to seem at the age of ten, especially those pesky questions involving double-digit numbers.