6. Multiplication strategies

Lesson

Let's try this problem to help us remember how to double a number.

Double 9.

Worked Solution

Idea summary

To double a number, we multiply the number by 2.

When we add the same number more than once, we can think of it as multiplication, as we see in this video.

Write this addition as a multiplication. 4+4+4+4

Worked Solution

Idea summary

If we are adding groups of the same size, we can also write it as a multiplication:

\text{Number of groups}\times\text{Amount in each group}

uses mental and written strategies for addition and subtraction involving two-, three-, four and five-digit numbers