Review: integer addition and subtraction (8th grade math)

I briefly review the basic principles governing integer addition and subtraction. For example: to add two integers with different signs, check "which side wins" (negative or positive). Subtract the absolute values of the two integers to find out by how much that "side" wins.

If you have many positive and negative integers to add, first add all the negatives together and all the positives, separately, and lastly add those two sums.

Another principle we look at is that any SUBTRACTION can be changed into an addition... the addition of the opposite of the number to be subtracted. This principle comes in handy if the calculation has both additions and subtractions.

Lastly we review how to add and subtract fractions when some of them are negative.

See also

Equations Review, Part 1 — video lesson

Math Mammoth Grade 8 curriculum

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