2*. In the picture you see 10 squares in a row with black and white disks.  To solve this puzzle you must get all the white disks and all the black ones together, but you can move two disks at a time. When you move them, you can jump over other disks, but you must always move two disks together and keep them in the same order.

3. A man went to the Zoo with a bag of nuts. At the Zoo he stopped near three cages of monkeys and decided to give the monkeys all his nuts. 'If I divide the nuts equally among the eleven monkeys in the first cage,' thought the man, 'one nut will remain. If I divide them equally among the thirteen monkeys in the second cage, eight nuts will remain. If I divide them among the seventeen monkeys in the third cage, three nuts will remain. And If I divide the nuts equally among the forty-one monkeys in all three cages or among the monkeys in any two cages, some nuts will remain too.' What is the smallest number of nuts that the man could have in his bag?

4. One day a bookkeeper noticed that the word balloon had in it two double letters, one after the other. 'Is there a word that has three double letters one after the other?' the bookkeeper thought. There is, and the word is on this page. Can you find it?

5. Take one letter away from the word zebra and rearrange the remaining letters so as to get another animal.

6*. Cut this 'E' into four pieces, and then try to make a square with these four pieces. When you draw the letter on a  sheet of paper, the proportions of it must be as they are shown in this picture.

7. 'How old are you, Mr. Brown?' Mr. Smith asked his friend. 'I forgot exactly,' was the answer. 'But my brother is two years older than I, my sister is four years older than he, my mother was twenty when I was born, and she told me yesterday that the average age of each of four members of our family (my brother, my sister, my mother and me) is thirty-nine years.' How old is Mr.. Brown?

8. Alfred had a very long walk to school every morning. When he got to the mosque, he had walked one quarter of the way, and it was usually half past eight style='color:red'> on the church clock when he passed it. When he got to the railway station, he had walked one third of the way and it was usually twenty five minutes to nine on the station clock when he passed it. At what time did he usually reach school?

9*. The boy has just drawn those straight lines which pass through each ball. While he drew the line, he did not take the pencil off the paper. Can you do the same thing with only two straight lines.

10. Twelve men had to get to a neighboring town, which was 20 miles away, as fast as possible, and they had to arrive there at exactly the same time. A man with a small car agreed to help them. 'I can do twenty miles an hour,' he said, 'but I can't carry more than four men at a time. How fast can you walk?' 'All of us can walk four miles an hour,' they answered. 'Very well,' said the driver, 'I'll go ahead with four men, drop them somewhere on the road, and they will walk. Then I'll return and take four more men (who will be somewhere on the road), drop them also, and return for the last four. So you must go on walking, and I'll do the rest.' As they started at noon, at noon, at what time did they all arrive?

11. A girl was sent to the well with two jugs. One of them could contain 7 litres and the other 11 litres. She had to bring back exactly 2 litres of water. How could she do it? What is the smallest number of times she had to fill and empty her jugs?

12*. A man had a large square field in which there were sixteen trees, as it is shown in the picture. He wanted (we don't know why) to put up five straight fences, so that every tree could be in a separate enclosure. How did he do it? Just take your pencil and draw five straight lines across the field so that every tree could be in a separate enclosure.

13*. A farmer once had a square piece of ground on which stood twenty four trees, exactly as it is shown in the picture. Before his death he decided to divide the ground among his eight sons. Each son had to receive the same amount of ground and the same number of trees. How was the ground divided?

14*. A lady had a very fine rug. 12ft by 9ft. It was damaged by fire. The lady was very sorry for the rug. So she cut from the middle a strip 8ft by 1ft, as shown in the picture. After that she tore the rug into two pieces and then out of these two pieces she made a square rug 10ft by 10ft. How did she do it?

15*. A lady had twenty pieces of material, all of the same triangular shape and size. She found that four of these pieces could form a square as it is shown in the picture. She decided to make a square rug out of all twenty pieces. Could she do it?

16. Can you find two cube numbers the difference of which will be a square number? The cube of 3 is 27, and the cube of 2 is 8, but the difference, 19, is not a square number. What are the smallest possible numbers?

17. Fred and Albert, with their father and the village postman, were standing near the river. They had to cross it, because their village was on the other side of the river. Fred and Albert each weighed 112 pounds. Their father and the postman each weighed 224 pounds. But the boat could carry only 224 pounds at a time. How did they cross?

18. At noon on Monday, Herbert asked his father what time it was. His father told him that it was noon and said that his watch was two minutes fast. On Wednesday morning, Herbert again asked the time and his father answered that the exact time was eight o'clock, but said that his watch was one minute slow. can you say at what time the watch of Herbert's father was exactly right?

19*. A miler had some sacks of flour and each sack had its own number. he arranged the sacks as it is shown in the picture below. Now you may see something curious about the figures. If we multiply the number on the left-hand pair, 28, by the number on the sack near  it, 7, we get 196, which is the number on the three sacks in the middle. But if we multiply the number on the right hand pair, 34, by the number on the sack near it, 5, we do not get 196. So the problem is to put the nine sacks so that each pair, when it is multiplied by its neighbor, will make the number in the middle.

20. Harry walked 117 miles, beginning on Sunday morning and finishing on Monday evening of the following week. He walked each day one mile father than the day before. How many miles did he walk each day?

21*. Here are eight cards with a number on each of them. Try to arrange them so that the sum of the two columns will be alike. Try to move as few cards as possible. Can you do it?

22. One day a naturalist told his friend: 'Bats usually sleep in dark corners during the day and wake up only at night. That's why most of the bats are blind, though some of them can see quite well and others can see with one eye. One day I caught a number of bats. Two of my bats could see with the right eye, three of them could see with the left eye, and five could not see with the right eye.' What is the smallest number of bats that the naturalist could have?

23*. A fly starting from the point A, can crawl round the four sides of the base of this cubical block in four minutes. Can you say how long it will take the fly to crawl from A to the opposite corner B?

24. 'How many marbles have you?' asked Fred's mother. 'Well, if you add one -quarter to one third of the number, you will have ten more than half of the number.' How many marbles had Fred?

25. Once Tom and his father went finishing. Tom caught a good fish and asked his father, 'How much can it weigh?' His father put his answer in the form of a little problem. 'Imagine, that the tail weighs 9 ounces; the head weighs as much as the tail and half the body; and the body weighs as much as the head and the tail together. Now, what is the weight of the fish?' Tom could not answer his father's question. Can you?

26. Harry was 12 years old when his father promised him a bicycle. 'I'll buy a bicycle for you when you are one third of my age,' said his father who was 56 years old then. When will Harry get a bike?