Rules for Signed Numbers

By Mr. Feliz

**Addition of Signed Numbers Rules**

Rule: When adding two numbers with the **same signs,** add the numbers and include the **same sign** in your answer.

Sample A:

(-4) + (-16) = -20....I simply added and kept the same sign.

Sample B:

(+20) + (+30) = +50....I simply added and kept the same sign.

NOTE: It is __not__ necessary to place a positive sign (our addition symbol) in front of numbers to indicate that they are positive. It is understood that a number **WITHOUT** a sign in front of it is positive.

Samples: +4 is the same as 4; 10 is the same as +10; +100 is the same

as + 100, etc.

Rule: When adding two numbers with **different signs,** subtract the numbers and include the sign of the **bigger number** in your answer.

Sample A:

-50 + (+5) = -45....I subtracted 5 from 45 and included the negative sign with my answer because 50 is the bigger number.

Sample B:

-6 + (+12) = +6....I subtracted 6 from 12 and included the negative sign with my answer because 12 is the bigger number. Also, note that +6 can also be written as 6 **WITHOUT** the positive sign.

Practice Questions:

1. 50 + (+9) =

2. 25 + (-50) =

3. (-40) + (-50) =

4. (-60) + (+60) =

5. 40 + 60 =

6. 200 + (-100) =

7. (-80) + (-80) =

8. (+5) + (+45) =

9. 50 + (-40) + (70) =

10. (-4) + (-5) + (-6) =

If you master signed number rules, algebra and beyond will not be a bad deal.