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Prime Magic

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Domino Magic Rectangle

An ordinary set of dominoes can be laid out as a 7 by 4 magic rectangle in which all the spots in all the columns add to 24, while those in the rows add to 42. Try it! Now try the magic square...

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Can you spot the similarities between this game and other games you know? The aim is to choose 3 numbers that total 15.

Street Lamps

Stage: 3 Short Challenge Level: Challenge Level:1

Note that there are 9 gaps between the lamps, so the total time is
(5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13) seconds = 81 seconds.

This problem is taken from the UKMT Mathematical Challenges.