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November 26, 2015
Posted by **brianna jackson** on Wednesday, September 28, 2011 at 5:40pm.

- math -
**MathMate**, Wednesday, September 28, 2011 at 6:07pmIf both numbers are >0, the sum is positive.

If both numbers are <0, the sum is negative.

If there is one + and one - sign, then

search the number with the bigger magnitude, i.e. choose the bigger number irrespective of the sign. The sign of the number with the bigger magnitude is also the sign of the sum.

4+5=? both positive, sum is positive

-4 -6 =? both negative, sum is negative

231 - 521 =?

+521 is bigger than +231, and since 521 is negative, so the sum is also negative. (=-290)

-341 + 425 = ?

425>341, but 425 is positive, so the sum is also positive (=+84)