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Welcome to perplexus.info, flooble's perplexing puzzle portal. Here, we collect all sorts of puzzles, from simple logic questions and word tricks to in-depth math problems like probability and geometry. Click around and see if your brain is up to the task! If you're new here, make sure you sign up so that you can leave comments and submit your own problems!
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Difficulty: 4 of 5 Latest: Just a search (in Numbers)
List all prime numbers below 3000 that can be expressed
as a^2 + n*b^2 for all integer n's from 1 to 10.
(No Solution Yet, 4 Comments) Submitted on 2018-08-18 by Ady TZIDON   
Difficulty: 3 of 5 Bonus: Spies Like Us (in General) Rating: 3.50
A particular restaurant is known for being a place spies like to hang out when discussing covert ops and contracts. The tables in this restaurant are set up by a grid, 7 by 7.

The spies, being secretive, pick the table furthest away from everyone else, and won't sit down next to an occupied table (not counting diagonally) for fear of being oveheard.

Naturally this presents a problem for the owner, as most of the seats where the first person sits, he won't be able to fit half or more in.

What seats should the owner mandate the first spy to sit?

If the owner's business grows and he uses a larger square grid, what sizes will be impossible for him to fit half or more?

For other grids, where should the first person sit to maximize the grid?
(No Solution Yet, 3 Comments) Submitted on 2007-07-30 by Gamer   
Difficulty: 4 of 5Ant highway (in Shapes)
Posted on 2018-08-17 by Jer (No Solution Yet, 3 Comments)
Difficulty: 3 of 5In Memoriam (in Numbers) Rating: 5.00
Posted on 2018-08-16 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 3 of 5Roll away (in Calculus)
Posted on 2018-08-15 by Jer (No Solution Yet, 4 Comments)
Difficulty: 2 of 5Tippy table (in Shapes)
Posted on 2018-08-14 by Jer (No Solution Yet, 2 Comments)
Difficulty: 2 of 531 created by 4 successive integers (in Numbers)
Posted on 2018-08-13 by Ady TZIDON (No Solution Yet, 6 Comments)
Difficulty: 2 of 5Jeopardy-style A&Q (in Numbers) Rating: 5.00
Posted on 2018-08-12 by Ady TZIDON (No Solution Yet, 6 Comments)
Difficulty: 3 of 5Quintuplet of consecutive primes (in Numbers)
Posted on 2018-08-11 by Ady TZIDON (Solution Posted, 1 Comments)
Difficulty: 3 of 5Attendance Records (in Numbers)
Posted on 2018-08-10 by Charlie (Solution Posted, 3 Comments)
Difficulty: 2 of 5Six or less? (in Just Math)
Posted on 2018-08-09 by Ady TZIDON (No Solution Yet, 6 Comments)
Difficulty: 3 of 5Art is marching on.. (in Word Problems)
Posted on 2018-08-08 by Ady TZIDON (No Solution Yet, 3 Comments)
Difficulty: 3 of 5Shirtless ? Even nude! (in Numbers)
Posted on 2018-08-07 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 2 of 5When P. meets F. (in Just Math)
Posted on 2018-08-06 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 4 of 57 in row (in Numbers)
Posted on 2018-08-05 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 3 of 5Goldbach's double (in Just Math)
Posted on 2018-08-04 by Ady TZIDON (No Solution Yet, 0 Comments)

Recently Posted Solutions:
Difficulty: 3 of 5Quintuplet of consecutive primes (in Numbers)
Submitted By Ady TZIDON. Solution posted on 2018-08-18 04:23:21
Difficulty: 4 of 5Call 911 (in Just Math)
Submitted By Ady TZIDON. Solution posted on 2018-08-17 08:57:37
Difficulty: 3 of 5Attendance Records (in Numbers)
Submitted By Charlie. Solution posted on 2018-08-13 14:29:44
Difficulty: 3 of 5Special feature (in Numbers)
Submitted By Ady TZIDON. Solution posted on 2018-08-06 20:58:39
Difficulty: 2 of 5Happy New Year (in Numbers)
Submitted By Ady TZIDON. Solution posted on 2018-08-05 15:18:55
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