## Search found 2 matches

### Floor sum

I've noticed Graham, Knuth (Concrete Mathematics, 2nd ed., p. 86) show how to do sum(floor(sqrt(k)), 0 <= k < n). Did anybody try and tackle sum(floor(sqrt(k (r / 2 - k))), 0 < k < r / 2)? This would actually solve a particular PE problem in closed form.

- Fri Nov 29, 2019 11:17 am
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 210
- Replies:
**70** - Views:
**23925**

### Re: Problem 210

I was also a bit dumbfounded at an invalid answer at the problem size, but I'm familiar with invalid rounding in Java in extreme cases. I feel such precision sub-problem is a charming feature of a PE problem. In this case however, changing the analysis and moving from square root to integers only se...