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'Triangular Clock' printed from https://nrich.maths.org/
Trinni is fascinated by triangular numbers (1, 3, 6, 10, 15, 21, etc.).
She found that she could rearrange the twelve numbers on a clock face so that each adjacent pair added up to a triangular number.
She left the 12 in its usual place; what number did she put where the 6 would usually be?
If you liked this problem,
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