I’ve found a method that the students have grasped fairly quickly for performing integer operations. It’s called the T-chart, and it works very well. The student creates a two column chart, one column is labeled with a + and the other with a -. Then the student places the values in their appropriate column. If the numbers are already in the same column, they add. If they are in different columns, they move the smaller of the two and subtract.
For example:
3 + -11
+ | -
3 | 11 (To represent 3 positives and 11 negatives)
They move the 3 under the 11 like so:
+ | -
__| 11
__| 3
(Ignore the underscores, this site won’t leave the space on the web page)
Since they moved the number, they subtract and get 8. Since 8 is in the negative column, the answer is -8.
Another example:
-3 + -9
+ | -
__| 3
__| 9
Since the two numbers are already in the same column, they add to get 12, and since it’s in the negative column, the answer is -12.
Hope this helps!
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