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Bosnia and Herzegovina JBMO TST 2011 Problem 4

Source: Bosnia and Herzegovina Junior Balkan Mathematical Olympiad TST 2011

September 16, 2018
combinatoricsnumber puzzle

Problem Statement

Let us consider mathematical crossword which we fill with numbers 00, 11, 22, 33, 44, 55, 66, 77, 88, 99 such that: 1) All digits occur exactly twice 2) 1010 horizontally divides 44 vertically 3) 4ā‹…4 \cdot (44 horizontally - 44 vertically +55) equals 11 vertically 4) 3636 divides 11 horizontally and 55 vertically 5) 99 vertically divides 55 vertically
In how many ways we can solve this mathematical crossword?
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