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IMAS 2012–2013 — Junior Division — Round 2 Question 12

IMAS · IMAS 2012–2013 — Junior Division — Round 2

Question 12

We put 130 identical balls into several identical boxes, such that the number of balls in each box is at least 10 but at most 20. The numbers of balls in the boxes are all different. How many distinct ways of putting these balls in the boxes are there?