Adding and Subtracting Positive and Negative Decimal Numbers

−28+(−8)=

• 36

• −36

• −20

• 20

-40 + 15.05

• 55.05

• 24.95

• -24.95

• 14.65

When adding decimals with the same sign you.....

• subtract and take the sign of the larger number

• add the opposite

• add and keep the sign

• subtract and keep the sign

When adding decimals with different signs you....

• subtract and take the sign of the larger number

• add the opposite

• add and keep the sign

• subtract and keep the sign

-51 + 81.623

• 30.623

• -30.623

• 132.623

• -132.623

-2.5 + (-2.5)

• -5

• 0

• 5

-2.5 + 1.3

• 6.3

• -1.2

• 6.79

• -5.1

-1.3 + 3.6 = ?

• 2.3

• -2.3

• 4.9

• -4.9

4.33 - .5

• -3.83

• 4.28

• -1.33

• 3.83

-12.4 + 9.2 + 1 

Mathematical Equivalence

ON