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> Logic> Probability> Shapes> General (3)
> Numbers> Games> Paradoxes> Riddles
> Just Math (1)> Science> Algorithms
You are free to look up the physical dimensions of the planet Earth, math formulas, physical constants etc using books, tables, Google etc. You are precluded to ask (i.e. Google) a direct question:

What is the total weight of Earth's atmosphere?

prior to posting your answer.

Please submit your estimate in a format N.PQ *10r kg.
Provide your reasoning as well.
We shall jointly evaluate the accuracy later.

(No Solution Yet, 2 Comments) Submitted on 2016-09-27 by Ady TZIDON   
Difficulty: 2 of 5 Bonus: Star of David (in General) Rating: 4.00
12 circular pieces (A-L) white on one side and blue on the other, are arranged in a "Star of David" as shown below, with the white face up.
                          A
                         / \
                        /   \
                 B-----C-----D-----E
                  \   /       \   /
                   \ /         \ /
                    F           G
                   / \         / \
                  /   \       /   \
                 H-----I-----J-----K
                        \   /
                         \ /
                          L
The goal is to turn all the 12 pieces so that they all show its blue side. At any time, you can turn any piece you want, but doing this, all the pieces that are connected to it, must be turned too. That is, if you choose to turn the "A"-piece (so that it becomes blue), the "C"-piece and "D"-piece must be turned too, becoming blue. If next you choose to turn the "E"-piece (so it becomes blue) the "G" and "D"-pieces must be turned too (the "G"-piece becomes blue, but the "D"-piece now becomes white again).

Can you devise a sequence with minimum turns to achieve the goal? Just name the pieces that you should turn; you donīt need to name the pieces that must be turned by the rule.

Iīm not forbidding using a computer (in fact, I canīt) but those who do, please give the others some time before posting a solution obtained by this way.
(Solution Posted, 10 Comments) Submitted on 2005-09-20 by pcbouhid   
Difficulty: 3 of 5Two Primes From Prime (in Just Math) Rating: 5.00
Posted on 2016-09-27 by K Sengupta (No Solution Yet, 2 Comments)
Difficulty: 2 of 5Number prediction (in Tricks)
Posted on 2016-09-26 by Charlie (No Solution Yet, 1 Comments)
Difficulty: 2 of 5Cryptajoke XV (in Cryptography)
Posted on 2016-09-26 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 3 of 5Immobile Hexominos (in Shapes)
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Difficulty: 3 of 5Nineteen Divisibility Nuance (in Algorithms)
Posted on 2016-09-24 by K Sengupta (No Solution Yet, 0 Comments)
Difficulty: 3 of 5Numbers' quantifiers (in Logic)
Posted on 2016-09-23 by Ady TZIDON (No Solution Yet, 4 Comments)
Difficulty: 2 of 5Nonnegative Sum Nuance (in Probability)
Posted on 2016-09-23 by K Sengupta (No Solution Yet, 1 Comments)
Difficulty: 3 of 5Find Function From Fraction (in Just Math)
Posted on 2016-09-22 by K Sengupta (No Solution Yet, 3 Comments)
Difficulty: 2 of 5Capital City Conclusion 3 (in General)
Posted on 2016-09-22 by K Sengupta (No Solution Yet, 1 Comments)
Difficulty: 3 of 5A cyclic path (in Geometry)
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Difficulty: 1 of 5Biting the Apple (in Tricks)
Posted on 2016-09-21 by Charlie (Solution Posted, 3 Comments)
Difficulty: 3 of 5Real roots from three dice (in Probability)
Posted on 2016-09-20 by K Sengupta (No Solution Yet, 1 Comments)
Difficulty: 1 of 5Easy sequence (in Sequences)
Posted on 2016-09-20 by Math Man (No Solution Yet, 1 Comments)
Difficulty: 3 of 5Area search (in Geometry)
Posted on 2016-09-19 by Ady TZIDON (Solution Posted, 2 Comments)

Recently Posted Solutions:
Difficulty: 1 of 5Biting the Apple (in Tricks)
Submitted By Charlie. Solution posted on 2016-09-23 07:54:01
Difficulty: 3 of 5Area search (in Geometry)
Submitted By Ady TZIDON. Solution posted on 2016-09-21 06:28:37
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