The 67858 Number Crunch
A monthly challenge that rewards sharp thinking with numbers. Free to enter, open to students, founders and number nerds alike.
1. Solve
Each month we post a real-world numbers puzzle — pricing, growth, probability or a number-pattern riddle.
2. Submit
Send your answer and a short explanation (max 200 words) using the form below before the deadline.
3. Win
A panel scores accuracy, clarity and creativity. Winners are announced on this page and by email.
The Rising Run
A store sells one product at a price that climbs 6%, then 7%, then 8% over three successive months, and then is discounted 58% in a clearance sale. Is the clearance price above or below 50% of the original price, and by how many percentage points? Show your working.
Tip: our percentage change and discount calculators help you check your logic.
Prize pool
- 🥇 1st: $100 (or sponsor-provided equivalent)
- 🥈 2nd: $50
- 🥉 3rd: $25
- ⭐ Best explanation: featured on our site + a free growth plan
Prize amounts depend on sponsor and reader support; the final prize pool is confirmed on this page before judging. Fund the prize pool or sponsor a contest.
Enter this month
Official rules (summary)
- No purchase or donation necessary to enter or win. Donating does not improve your chances.
- One entry per person per monthly challenge. Entries close at 23:59 UTC on the last day of the month.
- Open to individuals 18+ (or the age of majority in their jurisdiction). Void where prohibited or restricted by law. Employees of 67858.com and its sponsors are not eligible.
- This is a skill-based competition. Entries are judged on correctness (50%), clarity of explanation (30%) and creativity (20%). Judges' decisions are final.
- Winners are notified by email and must respond within 14 days; otherwise an alternate winner may be selected. Prizes are paid via an electronic method agreed with the winner and are non-transferable. Winners are responsible for any taxes.
- By entering, you grant 67858.com a non-exclusive licence to publish your explanation with credit.
- We may modify or cancel a contest if circumstances beyond our control arise, and will post any change on this page.
Past winners
The first season is underway — winners will be listed here after judging.