A robot moves on a square grid from the lower-left corner to the upper-right corner. It must take exactly 3 steps right and 2 steps up. How many shortest routes are possible?
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- The robot takes five steps in total.
- Choose the two positions for upward steps among the five steps.
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Answer: 10
Any route is specified by the places of two steps up among five steps. There are 10 ways to select these places.