Subtract Integers

Today we discussed the procedure to subtract integers.  Ex.  15 - (-21) =  We determined that to subtract integers you really have to add.

We use a process of LCO+ to work a subtraction of integers problem.  LCO+ stands for:

L - leave the first number alone
C - change the subtraction sign to an addition sign
O - change the next number, after the subtraction sign, to its opposite
+ - revert back to your addition rules because the problem is now addition

Ex.  15 - (-21) =

       15 + 21 = 36

The 15 stayed the same.  We changed the - sign to +, and the 21 changed from negative to positive.  The signs of the new problem are alike so we add them together.

Additional examples:

Ex.   -6 - (-8) =                               -9 - 7 =

        -6 + 8 =  2                              -9 + (-7) = -16