Multiplication

Four friends each get three scoops of ice cream, one egg costs 30 cents and you need ten of them: as soon as equal amounts show up several times, you're in the middle of multiplication. It's a shortcut that saves you a lot of counting. Best of all, with a few strategies you barely need to memorise anything.

Multiplying is repeated adding

3 × 4 means 3 groups of 4, so 4 + 4 + 4 = 12. You can see this best in a dot array: 3 rows of 4 dots each. Rotate the array and it becomes 4 rows of 3 dots, but the number of dots stays the same. That's why 3 × 4 = 4 × 3: in multiplication you may swap the numbers, just like in addition. By the way, the two numbers you multiply are called factors, and the result is called the product.

Times table strategies

You don't have to memorise every multiplication fact, you can derive many of them. Doubling is your best friend: 6 × 4 is double 6 × 2 = 12, so 24. And 8 × 6 is double 4 × 6 = 24, so 48. Multiplying by 10 is the easiest of all: with whole numbers you just attach a zero, 9 × 10 = 90. From anchor points like these you can build any fact you need.

Bigger numbers place by place

Splitting by place value helps with big numbers too. For 7 × 23, split the 23: 7 × 20 = 140 and 7 × 3 = 21, together 161. In the dot array this is one big field that you cut into two smaller ones. Every hard multiplication becomes two easy ones.