Pretend you are a jeweler. Sometimes people come in to get rings resized. When you cut down a ring to make it smaller, you keep the small portion of gold in exchange for the work you have done. Recently you have collected these amounts:
1.14 g 0.089 g 0.3 g
Now you have a repair job to do for which you need some gold. You are wondering if you have enough. How much gold have you collected? (NCTM P&S 2000, pp. 194-5)
This problem is intended as a motivation for developing algorithms for adding decimals. Students might check their ideas against a calculator's results.
Ignore the decimal points.
14 + 89 + 3 = 106, so the sum is 1.106 or 2.06.
Have you used this problem with a class and seen approaches other than(or more specific than) those mentioned above? Or do you have other comments or criticisms or stories? If so, please tell us!
Last updated 30 November, 2004