Math contest #7 Results and Solution
Solution:
The problem of the last contest was:
Find the nth prime and sum up all integers between and including 1 and the prime.
Finding the nth prime is the hardest part of this. You could do this by hand by writing down a few hundred numbers and checking manually for primes, or just use a computer program.
A formula for the sum(Σ) can be easily derived, by adding the sum and the reverse ordered sum:
Σ = 1 + 2 + … +(n-1)+ n
Σ = n +(n-1)+ … + 2 + 1
↓
Σ+Σ = n+1 + n+1 + … + n+1 + n+1 = n*(n+1)
↓
Σ = n*(n+1)/2
↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓
How your chance of winning is calculated:
- Every participant gets 1 point for entering the contest.
- Every solution entered gets 1 additional point.
- Multiple examples of a general solution count as one solution
- If there is only one general solution, those who found its pattern(by mentioning a general formula or showing more then 3 examples) will get an additional point.
- Your winning chance is
"your points"/"total points"
↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓
All participants did great and got the maximum score, but I list the score anyway.
List of participants with their scores and chance of winning, sorted by time of entry:
| Name | solutions found | score | chance of winning |
|---|---|---|---|
| @heraclio | prime and sum | 3 | 25% |
| @syalla | prime and sum | 3 | 25% |
| @tonimontana | prime and sum | 3 | 25% |
| @athunderstruck | prime and sum | 3 | 25% |
↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓
(Double) Winner draw(using a self written program):
Congratulations @athunderstruck and @tonimontana, you won 1 SBI each:
Hmm… I don't know away to send it to you now. I'll do the transfer as soon as steemit is working again.
↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓
Thanks ! :D