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Problem of the Week 974

The Broken Cash Register

I bought 4 items at a store having a broken cash register. The clerk used a calculator to add them up, but hit the multiplication key instead of the addition key and told me the result was $7.02. When I pointed out the error, he added them up and reported the same final bill! Is this possible, or was another error made?

Source: Folklore. But I saw it in a recent issue of Mathematics and Informatics Quarterly in a column by Harold Reiter.

© Copyright 2003 Stan Wagon. Reproduced with permission.

24 January 2003