1989 AHSME Problems/Problem 5
Problem
Toothpicks of equal length are used to build a rectangular grid as shown. If the grid is 20 toothpicks high and 10 toothpicks wide, then the number of toothpicks used is
Solution
There are 21 horizontal lines made of 10 matches, and 11 vertical lines made of 20 matches, and .
Alternatively, the frame can be dissected into L shapes, the right-hand border, and the bottom border: in which case the calculation is .
See also
1989 AHSME (Problems • Answer Key • Resources) | ||
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Followed by Problem 6 | |
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