Level 2 · Ages 8–11
Read it again any time, including while you work through the exercises.
Look at a chocolate bar: 4 rows of 6 squares. To count the squares, no need to point at them one by one! 4 rows of 6 is 4 × 6 = 24 squares. Multiplication is the art of counting groups in one go.
Times tables are your best allies: the better you know them, the freer your brain is to think about everything else. But nobody learns them by magic. The champion's secret is knowing how to REBUILD a forgotten result from what you already know.
First trick: order does not matter. 4 × 6 = 6 × 4, because turning the chocolate bar around does not change the number of squares. That cuts the work in half! Second trick: splitting. Forgot 6 × 7? Split it: 6 × 7 = 6 × 5 + 6 × 2 = 30 + 12 = 42. Third trick: easy stepping stones. Multiplying by 10 is easy, so 19 × 5 is 20 × 5 minus one group of 5: 100 - 5 = 95.
In this lesson, you will train your mental math with these tricks. Goal: rebuild any product in a few seconds, with or without a perfect memory!
You forgot 6 × 7. Rebuild it by splitting.
6 × 7 = 6 × 5 + 6 × 2
I split 7 into 5 + 2: seven groups of 6 is five groups of 6 plus two groups of 6.
6 × 5 = 30
I know the fives table well: 6 × 5 = 30.
6 × 2 = 12
Doubles too: 6 × 2 = 12.
30 + 12 = 42
I glue the pieces back together: 30 + 12 = 42. Result rebuilt!
Result: 6 × 7 = 42
Compute 19 × 5 in your head, without writing it down.
19 × 5 = 20 × 5 - 1 × 5
19 groups of 5 is almost 20 groups of 5: exactly one group is missing.
20 × 5 = 100
20 × 5 is easy: 2 × 5 = 10, so 20 × 5 = 100.
100 - 5 = 95
I remove the extra group of 5: 100 - 5 = 95.
Result: 19 × 5 = 95