The Lucky 7 Challenge
This month's puzzle: 17,777 is divisible by its own digit sum (29). It uses only the digits 1 and 7 and contains four 7s. Find the next number after 17,777 that uses only 1s and 7s, contains at least four 7s, and is divisible by its own digit sum.
Use any method — the decoder is allowed. Prize: a $77 gift card for one randomly drawn correct entry; runners-up get a feature in the newsletter.
Number Story creator challenge
Make a short video, post or graphic explaining a surprising fact about any number. Best entry wins $177 and is featured on our videos page. Send your link through the form with “creator challenge” in the answer box.
Tool idea prize
Suggest a number tool. If we build it, you get credit on the tool and a $27 thank-you. Send an idea.
Sponsor a prize
Put your brand on a contest seen by number-curious readers. See sponsorship options.
Official rules (summary)
- No purchase necessary. A purchase or donation does not increase your chances of winning.
- Eligibility. Open to individuals 18+ (or the age of majority in their jurisdiction). Void where prohibited. Employees and contractors of 017777.com and their households may not win.
- Entry period. Each monthly contest opens on the 1st and closes at 23:59 UTC on the last day of the month. One entry per person.
- Selection. One winner is drawn at random from all correct entries within 7 days of the close. Odds depend on the number of correct entries.
- Prizes. Prizes are as described, non-transferable, and may be substituted with a prize of equal or greater value. Winners are responsible for any taxes.
- Notification. Winners are emailed and must reply within 14 days or a new winner is drawn.
- Privacy. Entry data is used only to run the contest and, if you opt in, the newsletter. See the privacy policy.
- General. We may cancel or modify a contest if fraud or technical failure affects it. Contests are not sponsored, endorsed or administered by Google, YouTube or any social platform.
Questions
Do I need to buy anything to enter?
No. Entry is free. Purchases or donations do not improve your chances.
Who can enter?
Anyone 18 or older (or the age of majority where they live), except where prohibited by law. One entry per person per contest.
How are winners chosen?
All correct entries received before the deadline go into a random draw. Winners are contacted by email and announced on this page with their permission.