Arithmetic Grade Four

Lesson Nine: Subtraction Review

Order does matter with subtraction problems. You will remember with addition that we could write:

5 + 3 = 8 3 + 5 = 8

We can't do this with subtraction.

5 - 3 = 2 3 - 5 = -2 (a negative number)

You most likely did not deal with negative numbers in third grade. You don't need to know about them yet. The point though is that 5-3 does not produce the same difference as 3-5. (Remember the answer to a subtraction problem is called the difference.)

Just like with addition we can write a subtraction vertically or horizontally without it making any difference.

5 - 3 = 2 (horizontal arrangement of number sentence)

5 -3 (vertical arrangement of number sentence) ---- 2

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