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Out of Line
Age 11 to 14
ShortChallenge Level 
Fill in the empty squares with As, Bs, Cs, Ds and Es so that no horizontal, vertical or diagonal line contains a letter more than once (including diagonals like the one A and E are on). Which letter goes in the square marked *?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.
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