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BRAIN TEASERS ... |
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Feeling bored? Got a few minutes to spare? Here are 10 brain teasers for you to try and solve. Hints and answers are provided! There are no trick questions here, but some are easier than others ... My inspiration for many of these questions was The Puzzle and Humour Book, by G. A. Briggs. |
Arab Horses
A wealthy Arab left 17 horses to his three sons. However, he stipulated that the oldest son was to get half of the horses, the middle son was to get a third, and the youngest son was to get a ninth. How did they solve this conundrum, without slaughtering or selling any of the horses?
Travelling with Oranges
A traveller had a number of oranges, and was allowed to cross four bridges on his travels, on the condition that he handed over half of his oranges, plus half an orange, at each bridge. After crossing the fourth bridge he had no oranges left. How many did he start with?
Tennis balls
You have seven tennis balls, of which one is a little lighter than the other six. You also have a pair of balanced weighing scales, but no weights. How many weighings are necessary to find the light ball?
Joining the Dots
Consider 9 dots arranged in a three-by-three square. A well-known test of "lateral thinking" ability is to work out how to connect the dots, using just four lines and without going over the same line twice or taking pen from paper. Now consider 16 dots arranged in a four-by-four square. Can the 16 dots be connected using six lines, and under the same conditions?
Squares and Coins
Take 12 coins. It is easy to arrange them into a square, such that each side of the square has four coins along it. However, it is also possible to arrange the coins into a square such that there are FIVE coins along each side of the square. How?
Pay Rises
Two people applied for a job and were offered a salary of £20,000, to be paid half yearly, with the option of a rise of £3,000 per year, or £1,000 at each half year end. One applicant opted for the £3,000 per year rise. The other applicant opted for the £1,000 each half year and was offered the job. Why?
Crossing the River
Two sportsmen and their sons have to cross a river in their portable boat, which will only carry 100 kg at a time. Each of the men weighs 100 kg and each of the boys weighs 50 kg. How do they all manage to get across to the other side of the river?
Odd Numbers
The odd numbers are the numbers 1,3,5, ... . Take the first two odd numbers (1 and 3) and add them, and make a note of the total. Now take the first three odd numbers (1, 3 and 5) and add them, and make a note of the total. Repeat this for the first four, five and six odd numbers. Notice anything about how the totals relate to the sums you have just undertaken?
Sharing the Cash
How can you split the princely sum of £3 between two fathers and their two sons, without using a coin or note of less value than £1?
Cubes
A slightly tricky one to finish, but there is a hint in the title. Consider the five numbers 1, 153, 370, 371 and 407. What unique property do these numbers share? (No other numbers have this property).