How can doubling and halving help me multiply?

Fin and Snoot are building a rocket. They count and compare the bolts they each have.

How can doubling and halving help you multiply?

Everyone finds some numbers easier to work with than others.

If you have to multiply by a number you aren’t too sure about, it can sometimes help to half or double it.

Example

If you have to do 4 X 6 and you’re not sure about the 4 times table, remember that 4 is 2 X 2.

So you can half the 4 to make 2. Then you have to double the 6 to make up for this.

So instead of doing 4 X 6 you can do 2 X 12.

The answer is 24 for both.

How can adding help me multiply?
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How can an array help me multiply?
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