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Rounding Machine

Problem

A particular number machine works as follows.


E.g. 3.4 maps 6.8 maps 6 or 7.9 maps 15.8 maps 15

A different number machine does the following.


E.g. 3.4 maps 3 maps 6 or 7.9 maps 7 maps 14

Notice that 3.4 came out as 6 from both machines, whereas 7.9 came out differently. What must be special about a number for the same value to come out of each machine?

Problem ID: 97 (Jan 2003)     Difficulty: 2 Star

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