The number line is a familiar way to recall the rules of computing integers. In the example pictured above we see the numeral two as our starting point which is symbolized with a dot. This is followed by a subtraction sign, which leads us to move to the left three spaces as shown with curved line and arrow.
Helpful hints are another way that we can remember how to add and subtract integers.
We learned the first hint: Two like signs become a positive sign.
Example 2 - (-3) = ? This can be rewritten as 2 + 3 = ? since there are 2 like signs in the original problem.
Another example -3 - (-4) = ? Rewritten as - 3 + 4 =? Again like signs - and - turn into a positive sign.
And conversely the second hint: Two unlike signs become a negative sign.
Example 2 + (-2) = ? This is rewritten as 2 - 2 = ? because there are unlike + and - signs in the problem.
Another example -4 + (-2) = ? Rewritten as -4 - 2 ? We start at -4 on a number line, and move to the left (away from zero) 2 spaces. This leads us to -6 as the difference.
Now, we find the product or quotient of two integers to be:
Positive only when both integers are positive, or both are negative.
Examples: -4(-4) = -4 * -4 = 16 -24/-2 = 12
Negative when one integer is positive and the other is negative.
Examples 30/(-5)= -6 or -5(7) = -5 * 7 = -35
Which type of integer calculation do you find easiest to solve?
Try your skill with the interactive version of Integer Battleship found at the link below. After you make a locate a Battleship you'll be challenged with an integer problem to see if you can hit the target.
Integer Battleship
What are some other tips that you have for ways to calculate integers? Share a website, strategy you've learned from a teacher, or a way that helps you keep integer computation clear. What other games or activities have you done with Integers? Work at it and Integer computation will become automatic.
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