Negatives: Plus and Minus, Advanced

Objective

Know how to add and subtract large negative numbers

Example

2564 - (-3000) =

Answer: 5564

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Explanation

When we used small numbers, we were able to use number lines or imagine positives and negatives cancelling each other out.

-2 + 3

@ @ (2 negatives)

@ @ @ (3 positives)

@ @ (cancel out)

@ @ @

@ (1 positive left over)

With larger numbers, either of these approaches would take forever. Instead, we have to imagine what's happening, and turn it into adding or subtracting.

-2000 + 3000

Use your imagination.

• The first thing to think about is: after my positives and negatives cancel out, will there be positives left over, or negatives left over? Well, since 3000 is larger than 2000 , there will be positives left over.

• The second thing to think about is: how many will be left over. Well, since I had 3000 and the negatives cancelled out 2000 , that's the same thing as 3000 - 2000 .

3000

-2000

1000

Answer: 1000

To watch a Khan Academy Video, click here.

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Examples

Example 1

-2392 - (-1424)

-2392 + 1424 More negatives, so negatives will be left over

2392

-1424

968

Answer: -968

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Example 2

3342 + (-1424)

3342 - 1424 More positives, so positives will be left over

3342

-1424

1918

Answer: 1918

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Example 3

-1344 + (-7452)

-1344 - 7452 Both are negative, so we're just putting them together. So add

1344

+7452

8796

Answer: -8796

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Practice your skills