Math K-Plus

Subtracting Numbers, Subtracting Positive Numbers, Subtracting Negative Numbers

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What Are The Rules For Subtracting Positive Numbers And Negative Numbers?


Signed Numbers

Let's talk about Subtracting Positive Numbers And Subtracting Negative Numbers.

  • Subtracting Any Signed Number:
    (a) -5 - (-14) =
        -5 + 14 =
        14 - 5 = +8 = 8


    (b) -5 - (+14) =
        -5 - 14 =
        -14 - 5 = -19


  • Subtracting Quantities In Parentheses:
    Tip: Distribute the negative sign by flipping the sign on every term inside the parentheses:
    (a) 3 - (5 - 1) =
        3 + -5 + 1 = -1


    (b) 3 - (5 - 1) =
        3 + (-5 + 1) =
        3 + (-4) =
        3 - 4 =
        -4 + 3 = -1


  • Subtracting Product Quantities In Parentheses:
    Tip: Flip the sign only once for a product of two numbers.
    (a) 4 - (-5 × (-3)) =
        4 + (+5 × (-3)) =
        4 + (-15) =
        -15 + 4 = -11


    (b) 4 - (3 - 5 × (-3)) =
        4 + (-3 + 5 × (-3)) =
        4 + (-3 - 15) =
        4 -18 =
        -18 + 4 = -14


Here is more on how to use signed numbers: