Problem:
A block of calendar dates is shown. The order of the numbers in the second row is to be reversed. Then the order of the numbers in the fourth row is to be reversed. Finally, the numbers on each diagonal are to be added. What will be the positive difference between the two diagonal sums?
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Answer Choices:
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Solution:
The two sums are and , so the positive difference between the sums is .
Query: If a different block of dates had been chosen, the answer would be unchanged. Why?
The problems on this page are the property of the MAA's American Mathematics Competitions