Arithmetic Grade Four

Lesson Twenty-three: Whole Number Addition

We can use a number line to help us figure out the answer to an addition problem. Study this example:

This number line example illustrates the problem 18 + 8 = 26. The lines are pretty small and so we have to look at it carefully, but the green dot is above the 18 and the black dot is above the 26. The length of the line connecting the two dots is 8.


Here's another example for you to study:

Here we have a line of length 5. The green dot is above the 69 and the black dot is above the answer, 74. So, from this we can figure out that the problem illustrated here must be 69 + 5 = 74.

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