MathLabs

Problem 5

For each positive integer nn, the Bank of Cape Town issues coins of denomination 1n\tfrac{1}{n}. Given a finite collection of such coins (of not necessarily different denominations) with total value at most 99+1299+\tfrac12, prove that it is possible to split this collection into 100100 or fewer groups, such that each group has total value at most 11.
Step 6 of 6: Conclusion for k = 100
#{groups}≤k=100\#\{\text{groups}\} \le k = 100
Detailed analysis

There are gg complete groups of value 11 and r=100−gr=100-g boxes, each of value at most 11. Their total number is g+r=100g+r=100, proving the required partition.