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There are many situations, both in and outside of mathematics, where the process of doing and undoing helps you organize your activities and figure out how to reverse what you've done. In mathematics, it is often important to know how to undo an operation. Here are some examples from everyday life and mathematics:
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• | School buses pick up children every morning and then drop them off in the same spots every afternoon. Routes are usually organized by a "first on, last off" routine. |
• | You put on socks and then shoes every morning, and you take off shoes and then socks every night. |
• | If you added 3 to a number and got 724, you can get your original number back by subtracting 3. |
Sometimes you do things that can't be undone:
• | If the cover comes off the hot pepper shaker while you're sprinkling it on the pizza, there's not much you can do to undo the process. |
• | If you mix blue laundry detergent and water, you'd have a hard time separating them back into their original components. |
• | If you subtracted 10 from a number, then multiplied the result by itself, you wouldn't be able to find, with certainty, the original number just from undoing the steps. |
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