To subtract integers using Algebra Tiles make sure you have the small one unit squares cut out. It is a good idea to have 2 sets cut out or 54 squares. Remember, the colored side is the POSITIVE quantity and the blank, back side represents the NEGATIVE quantity. |
Click HERE to get your set of Algebra Tiles. | |
Once again, the trick to using algebra tiles to subtract integers is to make ZEROS. |
A
"zero" is made by placing a positive (colored tile) beside a
negative (plain tile).
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Let's say you have 3 and you want to subtract 4, or ( 3 - 4 = ? ) | Well, you could think of the subtraction problem as an "addition of the opposite" problem or 3 + (-4) = ? and then just use the addition approach. | |
OR you could use this rather interesting approach. | Start with three positive tiles and try to physically remove four tiles. | |
IMPOSSIBLE
you say. ....Not really. If we add a zero, it can be done. (remember, adding
zero does not change the value of anything) |
...
Zero and three more still equals three. However, now there are four positive tiles that can be removed!!! |
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When we pull the four
positive tiles off, we will be left with our answer, -1. |
3 - 4 = -1 | |
Let's try a harder
one. |
Start with five positive tiles and try to subtract seven negatives...... Once again, you say,"It can't be done!" and we say, "ADD SEVEN ZEROS AND then IT CAN BE DONE!" |
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Seven zeros plus five still equals five, but now we can pull off seven negative tiles and what we are left with will be the answer. | |
So you see 5 - (-7) = 12. You can actually TOUCH the problem! | ||
Now you try a few more on your own. You can always check
your answers on a calculator. |
Have fun "touching" those integer problems. |
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