Shipping Estimate
USA
- USA
- CAN
- USA
- CAN
Ships within 48 hours · Estimated delivery Jul 9 - Jul 14
Promo Codes Available:
For Your Every Summer RSVP, with Code: SUMMER15
Description
Puzzle Box, Volume 1Multiplying my age by 6 then subtracting 6 produces the same result as subtracting 7 from my age then multiplying by 7. How old am I? On my broken calculator with keys ] x =, the only functional number is 7. How can I get 34 to appear in the readout? A country mints four denominations of coins, in whole numbers of cents. It takes four of these coins to make 21 , or 24 , or 25 , or 26 . What are the denominations of the coins? These and almost 300
Multiplying my age by 6 then subtracting 6 produces the same result as subtracting 7 from my age then multiplying by 7. How old am I?On my broken calculator with keys ] - x =, the only functional number is 7. How can I get 34 to appear in the readout?
A country mints four denominations of coins, in whole numbers of cents. It takes four of these coins to make 21 , or 24 , or 25 , or 26 . What are the denominations of the coins?
These and almost 300 other mathematical puzzles appear in this original collection, devised by world-renowned mathematicians, puzzle creators, and devoted puzzle lovers. A unique puzzle project, it unites the efforts of a dozen authors, including software engineer Andrea Gilbert and Bram Cohen, author of the P2P BitTorrent protocol.
Seventeen different types of challenges include 3-D puzzles, chess puzzles, connections, dissections, foldings, geometrical puzzles, logic problems, matchstick puzzles, mazes, moving pieces, number puzzles, put-togethers, strimko, sudoku, visual puzzles, weightings, and word puzzles. The difficulty level of each puzzle is marked by stars, ranging from 2 to 5. Average difficulty level is about 3 stars, promising puzzle enthusiasts many entrancing hours of solving and enjoyment.
Binding Type: Paperback
Publisher: Dover Publications
Published: 11/16/2016
ISBN: 9780486810041
Pages: 96
Weight: 0.60lbs
Size: 10.90h x 8.20w x 0.20d
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.3 ★★★★★
Based on 1162 reviews
Sort
Product Reviews
★★★★★ 5
Value for your money
Qtips are better than other brands. Tried them all. The stick doesn't break. Good cotton. Cleaning performance grand!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 5, 2026
★★★★★ 5
The perfect toothbrush
Color: Pink
I finally found my perfect manual toothbrush. This after having used sonic are toothbrushes for many years now. This makes my teeth feels so clean afterward. The handle is a great length. It’s easy to hold and get into those spaces in the back of your mouth. The brushes are super soft and easy on the gums. The brushhead is just the right size. I feel this is a good price for a quality product. Not only that but it looks nice too!! I will be coming back for more.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 11, 2025
★★★★★ 5
Best Toothbrush I've EVER used!
Color: Mint
I'm 41 years old... & this may be the best toothbrush I've ever used in my life. The bristles are just perfect; super soft but tough enough to have your teeth feeling like you went to the dentist for a cleaning, gentle on the gums, & thin enough to clean in between your teeth. I honestly didn't want to stop & go over the 2 min just because it feels like a teeth massage. I will not be buying another toothbrush, I'm sticking with these!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 2, 2026
★★★★★ 5
a perfect manual toothbrush
Color: Mint
this is definitely my favorite toothbrush i've ever used. even though it's just a manual one, it's still my favorite. it's aesthetically pleasing and the bristles are perfectly soft so it doesn't hurt my gums (i naturally have sensitive and fragile gums). i love caps that covers bristles; it's a must if you keep your toothbrush in the bathroom and this toothbrush comes with a cap that clicks open instead of one that slides on and off, pretty unique and much more hygienic as it keeps the germs out much better.
i can't comment on the capabilities of the charcoal since i just received this but i can say that when i used it, i didn't feel any grit at all, so i believe boka's claim that the charcoal is soft enough to be safe for teeth (most of the time, charcoal is too gritty for teeth and ruins the enamel) the toothbrush is also pretty hefty so it's not cheap! paired with the boka toothpaste, my teeth feel so clean. now off to buy the whitening strips, floss, and mouthwash tablets from my new favorite brand!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 28, 2024
★★★★★ 5
Excellent
Color: Multi Color
I really like this product , it is plush means more fibers , it is not harsh plastic to blister your gums , for what it is very good price and quality.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 3, 2026
recommand products
925 Sterling Silver & Genuine Cognac Baltic Amber Ring - Adjustable - RG0871
115.00
Genuine Mix Baltic Amber Oval Shaped Luxurious Bracelet - BT0186
29.95
925 Sterling Silver & Genuine Cognac Baltic Amber Ring - Adjustable - RG0901
100.00
925 Sterling Silver & Genuine Cognac Baltic Amber Ring - Adjustable - RG0854
107.00
925 Sterling Silver & Genuine Cognac Baltic Amber Ring - Adjustable - RG0861
110.00