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How do you add two signed integers together?

Published in Mathematics 2 mins read

Adding two signed integers involves considering their signs. Here's how to do it:

Cases Based on Signs

There are two main cases to consider:

  1. Both integers have the same sign:

    • Add their absolute values (i.e., treat them as if they were both positive).
    • Keep the common sign.

    Example:

    • (+5) + (+3) = +8 (Both positive, add 5 and 3, keep the positive sign)
    • (-5) + (-3) = -8 (Both negative, add 5 and 3, keep the negative sign)
  2. The integers have different signs:

    • Subtract the smaller absolute value from the larger absolute value.
    • Use the sign of the integer with the larger absolute value in the result.

    Example:

    • (+5) + (-3) = +2 (5 > 3, subtract 3 from 5, keep the positive sign because 5 is positive)
    • (-5) + (+3) = -2 (5 > 3, subtract 3 from 5, keep the negative sign because 5 is negative)

Summary Table

Integer 1 Sign Integer 2 Sign Operation Result Sign Example
Positive Positive Add absolute values Positive (+4) + (+2) = +6
Negative Negative Add absolute values Negative (-4) + (-2) = -6
Positive Negative Subtract abs. values Sign of larger (+4) + (-2) = +2
Negative Positive Subtract abs. values Sign of larger (-4) + (+2) = -2

General Rule

In essence, you are either adding "more of the same" (same sign) or "balancing out" (different signs) with the sign of the larger force winning.

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