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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: 2 of 5 Latest: A logical search (in Numbers)
Find the smallest prime that remains prime
when added to its reversal

P&P solution preferred

(No Solution Yet, 0 Comments) Submitted on 2018-09-24 by Ady TZIDON   
Difficulty: 2 of 5 Bonus: In violation of Thermodynamics (in Science) Rating: 3.17
Many have heard the "old wives tale" stating that if you put hot water into a freezer, it freezes in less time than it would have if it had been cold to start. Never did I believe such a claim, as it runs contrary to one of the basic laws of nature.

While surfing one day on sites illustrating "bad science" I actually found a plausible real life reason why this in fact can be true (read:not always true, but possible). Running this experiment under controlled conditions [eg. measure the same volumes of hot and cold water, make sure containers are equal in any relevant aspect (shape, material, conductance properties, covered or not etc.), and that the freezer is properly set to achieve a uniform temperature throughout], can you come up with a reasonable set of conditions for which the water in the hot container would freeze before the water in the cold container?
(Solution Posted, 18 Comments) Submitted on 2003-05-11 by Cory Taylor   
Difficulty: 3 of 5Jeopardy style (in Just Math)
Posted on 2018-09-23 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 2 of 5A square divides concatenation (in Numbers)
Posted on 2018-09-22 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 3 of 5Antigrams wanted (in Word Problems) Rating: 5.00
Posted on 2018-09-21 by Ady TZIDON (No Solution Yet, 3 Comments)
Difficulty: 3 of 5Odd, but true (in Word Problems)
Posted on 2018-09-20 by Ady TZIDON (Solution Posted, 4 Comments)
Difficulty: 3 of 5Cash Box (in Numbers)
Posted on 2018-09-19 by Charlie (No Solution Yet, 0 Comments)
Difficulty: 3 of 5One rope, two flagpoles... (in Logic) Rating: 5.00
Posted on 2018-09-18 by Ady TZIDON (No Solution Yet, 4 Comments)
Difficulty: 2 of 5Name the sequence (in Sequences)
Posted on 2018-09-17 by Ady TZIDON (No Solution Yet, 5 Comments)
Difficulty: 4 of 531 days ago (in Word Problems)
Posted on 2018-09-15 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 2 of 5Always solvable (in Numbers)
Posted on 2018-09-15 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 3 of 5A packing exercise (in Shapes)
Posted on 2018-09-14 by Ady TZIDON (No Solution Yet, 5 Comments)
Difficulty: 2 of 5A formal proof requested (in Just Math) Rating: 3.00
Posted on 2018-09-13 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 2 of 5It is either O or E (in General)
Posted on 2018-09-12 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 2 of 5Lefties and righties 2 (in Logic) Rating: 3.00
Posted on 2018-09-11 by Math Man (No Solution Yet, 2 Comments)
Difficulty: 2 of 5Painless Problem (in Word Problems) Rating: 3.00
Posted on 2018-09-10 by Charlie (Solution Posted, 2 Comments)

Recently Posted Solutions:
Difficulty: 3 of 5Increasing sequences (in Just Math)
Submitted By Ady TZIDON. Solution posted on 2018-09-21 09:29:10
Difficulty: 3 of 5Odd, but true (in Word Problems)
Submitted By Ady TZIDON. Solution posted on 2018-09-21 08:21:41
Difficulty: 2 of 5Counting magic squares (in Just Math)
Submitted By Ady TZIDON. Solution posted on 2018-09-21 08:04:54
Difficulty: 2 of 5Painless Problem (in Word Problems)
Submitted By Charlie. Solution posted on 2018-09-16 09:58:17
Difficulty: 3 of 510-Word Square (in Word Problems)
Submitted By Charlie. Solution posted on 2018-09-06 09:56:24
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