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# Puzzles and Brain Teasers

Brain teasers and puzzles help you to train your brain. So go ahead, take our Brain Teaser. And don't take a peek at the answer until you have tried really hard.

## Brain Teasers and Puzzles

All the girls of Mary's class are standing in a row. Mary is the 11th girl from both ends. How many girls are studying in Mary's class?

21 girls

1 2 3 4 5 6 7 8 9 10 11 10 9 8 7 6 5 4 3 2 1

Complete the series
25 32 37 47 58 71 79 __ __

95, 109

Add the sum of the digits of the number to the number to get the next one. Hence,
25 + 2 +5 = 32
32 + 3 + 2 = 37
37 + 3 + 7 = 47
47 + 4 + 7 = 58 and so on.

Find the odd one out:
First, Second, Third, Forth, Fifth, Sixth, Seventh, Eighth

Forth (it should be fourth)

Fill in the sequence:
A C F H K M _

P

Six glasses are in a single row. First three glasses are filled with water and the rest are empty. Move only one glass so that empty and filled glasses are aligned alternately.

Pour water from the second glass into the fifth one.

What is the missing number?

11
6+4+3 -2 = 11

Connect all the dots with only 4 straight lines without lifting the pencil.

Using four 7s and one 1 make 100. You can use (), /, X, +, -

177-77 = 100

Remove 6 pins to make 10:

1. Remove pins from the left, right and bottom of the first figure. (3)
2. Remove pin from the bottom of the second figure (1)
3. Remove pins from the top and bottom of the third figure (2)
3+1+2 = 6

Justify the equation by shifting only one number:
62 - 63 = 1

26 - 63 = 1
(2x2x2x2x2x2) - 63 = 1
64 - 63 = 1

Fill in the blanks: 18, 11, 15, 14, 19, ___, ___,10, ___, ___, 20

17, 16, 13, 12

The numbers are arranged in alphabetical order.

A farmer has 30 animals consisting of chickens and cows. The animals have 74 legs in total. Find out the number of chickens and cows the farmer has.

23 Chickens and 7 Cows

Let the number of chicken be X and number of cows be Y
X+Y = 30
Chickens have 2 and cows have 4 legs.
Hence,
Number of legs chickens have = 2X
Number of legs cows have = 4Y
2X + 4Y = 74.
Putting X = 30 - Y (from first equation)
2(30 - Y) + 4y = 74
60 - 2Y + 4Y = 74
2Y = 14
Y = 7

X = 30 - 7
X = 23

The farmer has 7 cows and 23 chickens.

If the price of 20 chocolates is \$40, what is the price of 1 score of chocolate at \$2 each?

\$40

1 score = 20

Insert the missing alphabets to complete the series.
T,  F, S, E, T, T, F, _, _, _, _, T, T, T, T

S,E,T,T

The first "T" stands for Two. Now go on adding 2 to the series and take the first letter: Four, Six, Eight, Ten, Twelve, Fourteen. This way, we will get Sixteen, Eighteen, Twenty, Twenty-two or S, E, T, T.

A man took a cab from his home to reach office. On the way back, he took a cab again. When he had reached his office, he paid 1/6th of what he had in his wallet and when he returned home, he paid 1/5th of what he had left in his wallet. In the first trip the fare was \$60. How much money did he initially have and how much is left with him now?

\$360 & \$240 respectively.

Let the initial amount in his wallet be 'X'. In the first journey, he paid 1/6th of X which we know is \$60. So the equation is
16 x X = 60
X6 = 60
X = 360
Hence, the initial amount is \$360.

Now that he has paid \$60 for the first trip, he is left with \$(360-60) = \$300.

In the return trip he pays 1/5th of what he had left which was \$300. So if he pays 'Y' for the return trip, then the equation is
Y = 15 x 300
Y = 60
Hence after the return trip, he is left with \$(300-60) = \$240.

John has an examination a day after tomorrow. Although he intended to start his preparations five days before the examinations, he could start with it just two days before yesterday. If today is Saturday, when did he expect to start his preparations and when did he actually start?

He had expected to start his preparations on Wednesday, and started it on Wednesday itself.

What comes next in the sequence?
1049760   58320   3888   324   36   6   _

2

Here is how we get the sequence:
1049760/58320 = 18
58320/3888 = 15
3888/324 = 12
324/36 = 9
36/6 = 6
Going by this trend, the last equation should be
6/? = 3
Hence, 2 is the correct answer.

The owner of a stationery shop uses a special method to price the items which he sells in his shop. A pencil costs \$36, ruler costs \$30, pen costs \$18 and a book costs \$24. How much does a notebook then cost?

\$48

He charges \$6 for every letter used to spell that item.

Once I challenged my neighbor for a game of chess everyday for an entire month consisting of 31 days. It was decided that whoever won after every match would be entitled to get \$2 dollars from the loser and the entire money won would be paid at the end of the month. At the end of the month, my neighbor paid me a balance amount of \$38 dollars. He had won 5 matches. How many matches did I win and how many ended in draw?

I won 24 and 2 ended in draw.

My neighbor won 5 matches which means that I owed him \$10. However, he paid me \$38 which means that I must have won \$48 worth of matches. This converts to 24 matches.

Now if I won 24 matches, and my neighbor won 5, then the number of draws were 2 (31 - 24 - 5 = 2)

A check grand prix was organized in a knock-out format. After every match, the loser would be eliminated. The number of participants were 256. How many matches were played?

255

This is because all players except the champion have to lose one match.

We have 1 final where 2 players play.
We have 2 semi-finals where 4 players play. Thus, number of matches is 1 + 2 = 3.
We have 4 quarter-finals where 8 players play. Thus, number of matches is 3 + 4 = 7.
We have 8 pre-quarter-finals where 16 players play. Thus, number of matches is 7 + 8 =15.
We have 16 4th round matches where 32 players play. Thus, number of matches is 15 + 16 = 31.
We have 32 3rd round matches where 64 players play. Thus, number of matches is 31 + 32 = 63.
We have 64 2nd round matches where 128 players play. Thus, number of matches is 63 + 64 = 127.
We have 128 1st round matches where 256 players play. Thus, number of matches is 127 + 128 = 255.

A chess tournament was organized in a round-robin format. Each player had to play the other participants in the tournament once. At the end of the tournament it was seen that a total of 120 matches were played. How many players participated in the tournament?

16 players participated in the tournament.

If 16 players participated, then the first player played matches against the other 15 players. The second player has already played against the first player, and so has to play matches against only the other 14 players. In this manner, the second-last player has to play against only one player, and the last player has already played against all the players. Thus, the total number of matches is:
15 + 14 + 13 + 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 + 0 = 120.

Suppose there are 16 birds. Now if one-fourth of those birds fall from the air and out of that one-fourth, one-third dies. Then how many birds are alive?

All 16 because birds can never fall from the air, they can fly. Isn't it?

A poor vendor, who had just one sack with him, went to a restaurant to sell salt and sugar. However, since he was having just one sack and obviously he could not mix the salt and sugar, so he had poured in the salt first, tied the sack in the middle, and then filled the top portion of the sack with the sugar. But the restaurant owner decided to buy salt only as he did not have any requirement for sugar. How did the vendor transfer the salt from his sack to the restaurant owner's sack?

Now, there were certain conditions:

• If the vender poured the sugar anywhere else than either of the two a sacks, it would become unfit for selling.
• The restaurant owner refused to exchange his better quality sack with the old one of the vendor.
• No matter how old his sack was, the vendor could not afford to cut a hole in his sack.

At first, the sugar was poured into the restaurant owner's sack. Then it was tied from the middle and turned inside out. After this, the salt was poured into the restaurant owner's sack. Then in this position, it was untied from the middle and the sugar was poured back to the vendor's sack.

A basket contains 5 mangoes. How can you divide them among 5 kids so that each one has a mango and one mango stays in the basket?

Give one mango each to the four kids and give the fifth kid the mango along with the basket.

How many times can you subtract the number 5 from the number 40?

Just once because once you subtract 5 from 40, it becomes 35. Next time when you subtract 5, you are doing it from 35 and not 40.

If you are supposed to take pills at half an hour intervals, how many minutes would 5 pills last?

120 minutes or 2 hrs. 5 pills can be taken over 4 half an hour intervals. Hence 4x30 = 120 mins.

What is common to each of the following?
• Banana
• Dresser
• Grammar
• Potato
• Revive
• Uneven
• Assess

Detach the first letter of each word and append it to the end. The new word will read the same as the original word when read from right to left.

Introducing a lady to her friend, Juliet said, "Her father-in-law's father's only son's, only daughter's brother, is grandfather to my daughter." How is the woman related to Juliet?

Note: My daughter's father's grandfather had only one son and one daughter.

You have two vessels. One has a capacity of 8 gallons and the other of 3 gallons. How do you use them to get exactly 7 gallons of water?

Note - You cannot estimate by pouring out a random amount of water from or into any of the vessels. Also you cannot use any other vessel (s) besides these two, nor are you allowed to make any marking(s) on the vessels.

Operation 8 gallon vessel (Vessel P) 3 gallon vessel (Vessel Q)
Initially 0 0
Fill P 8 0
Take out 3G from P into Q, by filling Q to the brim 5 3
Empty Q 5 0
Again, take out 3G from P into Q, by filling Q to the brim 2 3
Empty Q 2 0
Pour remaining 2G from P into Q 0 2
Fill P 8 2
Fill Q up to brim by pouring out water from P and 7G will remain in Q 7 3

At what time will the hands of a clock (the minute hand and the hour hand) come together after 3:00 pm?