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Math / Integers / Grade 7 / mi7c1

Signed Changes: Follow the Number Line

Use a starting position and a signed change to explain each result.

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Adding a positive number moves right; adding a negative number moves left. To subtract a number, add its opposite. Count intervals, not the starting tick. Check an answer by reversing the change.

Worked example

-2 - (-5) = -2 + 5 = 3. Start at -2, move five units right, and finish at 3. Check: 3 + (-5) = -2.

A number line with equal intervals from -8 to 8. An arrow starts at -2 and ends at 3: subtracting -5 means adding positive 5.
Worked model: subtract a number by adding its opposite.
Question 1 Start at -4 and add 7. Where do you finish?
Question 2 Calculate 2 + (-6).
Question 3 Calculate -3 - 5.
Question 4 Calculate -5 - (-8).
Question 5 Calculate -7 + 7.