All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info
Welcome to, 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!
> Logic> Probability> Shapes> General
> Numbers (3)> Games> Paradoxes> Riddles
> Just Math> Science> Algorithms
Before trying the problem "note your opinion as to whether the observed pattern is known to continue, known not to continue, or not known at all."

Let P(n)= The product of the first n primes.

P(n)+1 is like Euclid's method to show there are infinitely many primes, and may or not be prime itself. Now look at the difference between P(n) and the next prime after P(n)+1.

n=1, 5-(2)=3
n=2, 11-(2x3)=5
n=3, 37-(2x3x5)=7
n=4, 223-(2x3x5x7)=13
n=5, 2333-(2x3x5x7x11)=23
n=6, 30047-(2x3x5x7x11x13)=17
n=7, 510529-(2x3x5x7x11x13x17)=19
n=8, 9699713-(2x3x5x7x11x13x17x19)=23

Are these differences always prime?

(No Solution Yet, 0 Comments) Submitted on 2017-09-21 by Jer   
Difficulty: 4 of 5 Bonus: Dinner and Dialogue (in General) Rating: 3.67
The Dinner and Dialogue Club has planned a series of small meetings. Each meeting would consist of two or three members enjoying friendly conversation with each other while eating food from different places all over the world. Each member is scheduled to meet exactly four times. No pair of members will meet twice, but some pairs might not meet at all.

The first thing the club did was schedule and arrange the meetings so that each member knew whom to meet and when. When it came to choosing restaurants, someone suggested that each member eat at two restaurants with eastern food, and two with western food (each restaurant is either one or the other). They liked the idea, but to their dismay, the idea was not possible without rearranging at least some of the meetings.

What possible meeting schedule might cause this to happen? How many members are there in this club, at the least?

(Solution Posted, 9 Comments) Submitted on 2005-11-02 by Tristan   
Difficulty: 2 of 5The next five... (in Sequences)
Posted on 2017-09-20 by Charlie (No Solution Yet, 2 Comments)
Difficulty: 3 of 5Does it continue? 3: Growing table of primes (in Numbers)
Posted on 2017-09-19 by Jer (No Solution Yet, 3 Comments)
Difficulty: 2 of 5Parabolic Numbers (in Just Math)
Posted on 2017-09-18 by Charlie (No Solution Yet, 2 Comments)
Difficulty: 3 of 5Proving an inequality (in Geometry)
Posted on 2017-09-17 by Ady TZIDON (No Solution Yet, 0 Comments)
Difficulty: 3 of 5Does it continue? 2: Prime or not? (in Numbers)
Posted on 2017-09-16 by Jer (No Solution Yet, 4 Comments)
Difficulty: 4 of 5Reverse Engineering (in General)
Posted on 2017-09-15 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 2 of 5Cryptaquote I (in Word Problems) Rating: 5.00
Posted on 2017-09-14 by Ady TZIDON (No Solution Yet, 6 Comments)
Difficulty: 2 of 5Does it continue? 1: Chord regions (in Sequences)
Posted on 2017-09-13 by Jer (No Solution Yet, 9 Comments)
Difficulty: 3 of 5Sans squares (in Sequences)
Posted on 2017-09-12 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 2 of 5MMMMMM Donut (in Just Math)
Posted on 2017-09-11 by Jer (No Solution Yet, 4 Comments)
Difficulty: 3 of 5Lots of lods (in Sequences) Rating: 4.67
Posted on 2017-09-10 by Ady TZIDON (No Solution Yet, 7 Comments)
Difficulty: 4 of 5Parallelograms (in Geometry)
Posted on 2017-09-09 by Bractals (Solution Posted, 5 Comments)
Difficulty: 3 of 5An unsolved double murder (in Logic)
Posted on 2017-09-08 by ollie (No Solution Yet, 0 Comments)
Difficulty: 4 of 5Product of 100 factorials (in Just Math) Rating: 3.50
Posted on 2017-09-07 by Ady TZIDON (No Solution Yet, 8 Comments)

Recently Posted Solutions:
Difficulty: 4 of 5Parallelograms (in Geometry)
Submitted By Bractals. Solution posted on 2017-09-19 16:26:36
Difficulty: 3 of 5Topical Quotation VII (in Word Problems)
Submitted By Charlie. Solution posted on 2017-09-11 14:15:01
Difficulty: 3 of 5Fifty-fifty? (in Probability)
Submitted By Ady TZIDON. Solution posted on 2017-09-06 02:18:00
Difficulty: 3 of 5Next Numbers Please #9 (in Numbers)
Submitted By Brian Smith. Solution posted on 2017-09-03 12:58:42
Difficulty: 3 of 5One more line (in Logic)
Submitted By Ady TZIDON. Solution posted on 2017-09-02 23:57:23
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (4)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2017 by Animus Pactum Consulting. All rights reserved. Privacy Information