2007 AMC 8 Problems/Problem 9
Contents
[hide]Problem
To complete the grid below, each of the digits 1 through 4 must occur once in each row and once in each column. What number will occupy the lower right-hand square?
Solution
The number in the first row, last column must be a due to the fact if a was in the first row, second column, there would be two threes in that column. By the same reasoning, the number in the second row, last column has to be a . Therefore the number in the lower right-hand square is .
Solution 2
Note how the first and second row already contain a . Since the third row, last column already has a , the only possible place a could be in is the bottom right square. Thus our answer is .
See Also
2007 AMC 8 (Problems • Answer Key • Resources) | ||
Preceded by Problem 8 |
Followed by Problem 10 | |
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