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### Top 20 Popular Puzzles

Top 20 Popular Puzzles
Popular Puzzles 11 : Weighing Balance Puzzle
Difficulty ★★★★☆     Popularity ★★★★☆

You can place weights on both side of weighing balance and you need to measure all weights between 1 and 1000. For example if you have weights 1 and 3,now you can measure 1,3 and 4 like earlier case, and also you can measure 2,by placing 3 on one side and 1 on the side which contain the substance to be weighed. So question again is how many minimum weights and of what denominations you need to measure all weights from 1kg to 1000kg.

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Popular Puzzles 12 : Trick Question
Difficulty ★★★☆☆     Popularity ★★★★☆

Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

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Popular Puzzles 13 : Puzzle Boat
Difficulty ★★★★☆     Popularity ★★★★☆

At the local model boat club, four friends were talking about their boats.

There were a total of eight boats, two in each colour, red, green, blue and yellow. Each friend owned two boats. No friend had two boats of the same colour.

Alan didn't have a yellow boat. Brian didn't have a red boat, but did have a green one. One of the friends had a yellow boat and a blue boat and another friend had a green boat and a blue boat. Charles had a yellow boat. Darren had a blue boat, but didn't have a green one.

Can you work out which friend had which coloured boats?

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Popular Puzzles 14 : Building Puzzle
Difficulty ★★★★☆     Popularity ★★★★☆

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

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Popular Puzzles 15 : Find next number in series
Difficulty ★★☆☆☆     Popularity ★★★☆☆

What are the next two numbers in this sequence?

7, 14, 17, 21, 27, 28, 35, 37, ?, ?

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Popular Puzzles 16 : Aeroplane Hardest Quiz
Difficulty ★★★★★     Popularity ★★★☆☆

The puzzle question is : On Bagshot Island, there is an airport. The airport is the homebase of an unlimited number of identical airplanes. Each airplane has a fuel capacity to allow it to fly exactly 1/2 way around the world, along a great circle. The planes have the ability to refuel in flight without loss of speed or spillage of fuel. Though the fuel is unlimited, the island is the only source of fuel.
What is the fewest number of aircraft necessary to get one plane all the way around the world assuming that all of the aircraft must return safely to the airport? How did you get to your answer?
Notes:
(a) Each airplane must depart and return to the same airport, and that is the only airport they can land and refuel on ground.
(b) Each airplane must have enough fuel to return to airport.
(c) The time and fuel consumption of refueling can be ignored. (so we can also assume that one airplane can refuel more than one airplanes in air at the same time.)
(d) The amount of fuel airplanes carrying can be zero as long as the other airplane is refueling these airplanes. What is the fewest number of airplanes and number of tanks of fuel needed to accomplish this work? (we only need airplane to go around the world)

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Popular Puzzles 17 : Sound Series Pattern
Difficulty ★★☆☆☆     Popularity ★★★☆☆

Can you figure out the logic I used to decide the order of the following words: gun, shoe, spree, door, hive, kicks, heaven, gate, line, den

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Popular Puzzles 18 : Missing Number in this Sequence
Difficulty ★★☆☆☆     Popularity ★★★☆☆

Can you discover the missing number in this series?

37, 10, 82
29, 11, 47
96, 15, 87
42, ?, 15

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Popular Puzzles 19 : Simple Simple Google Interview Puzzle
Difficulty ★★☆☆☆     Popularity ★★★☆☆

The puzzle is if the shopkeeper can only place the weights in one side of the common balance. For example if shopkeeper has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names the weights you will need to measure all weights from 1 to 1000. This is a fairly simple problem and very easy to prove also.  Answer for this puzzle is given below.

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Popular Puzzles 20 : Paradox Probability Puzzle
Difficulty ★★★☆☆     Popularity ★★★☆☆

This is a famous paradox which has caused a great deal of argument and disbelief from many who cannot accept the correct answer. Four balls are placed in a hat. One is white, one is blue and the other two are red. The bag is shaken and someone draws two balls from the hat. He looks at the two balls and announces that at least one of them is red. What are the chances that the other ball he has drawn out is also red?