Arithmetic Grade Four

Lesson Twenty-one: Whole Number Addition

Another way of illustrating addition problems is to use a number line like this:

8 + 7 = 15 The green dot represents the first number in the problem (8 in this case). The blue line represents the amount that you add to the first number (7 in this case). The black dot represents the answer to the problem (15 in this case).

Here's another example:

4 + 8 = 12 We have 4 + 8 = 12 as our problem in this example. The green dot is positioned above the 4. The blue line is 8 segments long. The black dot is positioned above the 12.

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