Idea 4of 24Builds onTimes 0 and times 1
Double, then double again
How does 4 × 6 help you find 8 × 6?
Today you'll discover
- why 8 rows is two blocks of 4 rows
- how doubling builds the 4s and 8s
- how halving works too
Think first8 rows of 6 dots
You know 4 × 6 = 24. What is 8 × 6?
Decide first, then press Next. Look for two equal blocks in the array.
8 rows of 6 dots. A dashed line cuts it after 4 rows: the top block is orange, 4 × 6 = 24, the bottom block blue, 4 × 6 = 24. Then double 24 gives 8 × 6 = 48. The last step shows 4 rows of 7.
See the whole ideathe big idea and the key word, in one place
The big idea
Doubling turns a 2s fact into a 4s fact, and a 4s fact into an 8s fact.
Double again and again
Each fact is double the one before.
- 2 × 612
- 4 × 624
- 8 × 648
Where it goes nextHalving works too: 5 × 8 is half of 10 × 8 = 80, so 5 × 8 = 40.
Key word
- doubling
- adding a number to itself, the same as multiplying by 2: double 24 is 48
Ready to use it?
- Double a 2s fact to find a 4s fact.
- Double a 4s fact to find an 8s fact.