Lesson

Multiplication looks at equally sized groups. Doubling means multiplying equally sized groups by 2. Let's try this problem to remember how.

Find the value of 9\times2.

Worked Solution

Idea summary

Multiplying by two is the same as doubling and can be thought of as the total of two equally sized groups.

4 groups is twice (two times) as many as 2 groups. 8 groups is twice (two times) as many as 4 groups. Let's look at how to multiply numbers by 8 using a Double, Double, Double strategy.

Find the value of 8 \times 5.

Worked Solution

Idea summary

You can use the Double, Double, Double strategy to multiply a number by 8. To do this, double the number, double the answer, then double the answer again.

uses mental and informal written strategies for multiplication and division