Entry no. 8

22. A man goes out for a walk. He walks south one mile, east one mile, and north one mile, and ends up in the same place he started. He didn't start out at the north pole -- so where did he?

23. You're a cook in a restaurant in a quaint country where clocks are outlawed. You have a four minute hourglass, a seven minute hourglass, and a pot of boiling water. A regular customer orders a nine-minute egg, and you know this person to be extremely picky and will not like it if you overcook or undercook the egg, even by a few seconds. What is the least amount of time it will take to prepare the egg, and how will you do it?

24. How can you express 100 using exactly six 9 digits and such symbols: + - / * ?

Good Luck!
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ANSWERS:
16. Push the cork into it, than shake the coin back out.
17. Cut it by the dimensions into four equal pieces (two cuts) than cut it horizontally in the middle of the cake. Voila!
18. Almost all of it. Climb the first rope up to the ceiling, cut it to an extent it bares your weight but would break if you swing or jump. Get down. Repeat this with second line. Than climb first one up to two-three meters and swing and jump, breaking the line up near to the ceiling. Repeat with the second one.

Entry no. 7

19. If a boy and a half can eat a hot dog and a half in a minute and a half, how many hot dogs can six boys eat in six minutes?

20. Reason why 304140932017133780436126081660
64768844377641568960512078291027000 (treat as one number) cannot possibly be the value of 50 factorial, without actually performing the calculation.

21. If you can buy eight eggs for 26 cents, how many can you buy for a cent and a quarter?

Good Luck!
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ANSWERS:
13. You have to do it with a camera, not a hairdryier.
14.One pound of feathers is more than one pound of gold because the "pound" unit is different. The most commonly used system of weights in the US and Great Britain is the avoirdupois system, where 1 pound = 16 ounces. This is used for most solid objects, except for precious metals and gems; gold is weighed by a special system, called the troy system, where one troy pound = 12 troy ounces. Where one avoirdupois ounce is 28.35 grams, one troy ounce is about 31.10 grams. To convert from avoirdupois pounds to troy pounds, multiply the first by 1.2152 to get its equivalent in troy measurement. Therefore, one "pound" of feathers in troy weight is actually 1.2152 pounds (one avoirdupois pound), compared to one troy pound of gold. And the feathers win.
15. Nothing. Really, 9.(9) equals exactly 10.

Entry no. 6

16. If you put a coin in an empty bottle and insert a cork into the neck of the bottle, how could you remove the coin without taking the cork out or breaking the bottle?

17. You must cut a circular birthday cake into exactly eight equal pieces, but you're only allowed to make three straight cuts, and you can't move pieces of the cake. How can you do it?

18. Two fifty foot ropes are suspended from a forty foot ceiling twenty feet apart. You have only a knife. How much of the rope can you steal?

Good Luck!
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ANSWERS:
10. A towel.
11. 2, of course. That was easy, wasn't it?
12. Every of friends would have to travel 18 miles. With the velocity of 6 miles per hour it will take them 3 hours. Pidgeon would fly for 3 hours as well, with its velocity of 18 mph, so- 54 miles.

Entry no. 5

13. Why can't you take a picture of Amazon Indian women with a hair dryier?

14. What weights more: a pound of feathers or the pound of gold?

15. The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

              a =  9.999999...
           10a = 99.999999...
       10a - a = 99.999999... - 9.999999...
            9a = 90
             a = 10 

Good Luck!
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ANSWERS:

7. Right, of course. Try to put a mirror near to the glove to find out why.
8. 'I will be shot.'
9. Place a paper on the cylinder, than simply draw the circle.

Entry no. 4

Not all are so much math, but still...

10. What gets wetter and wetter the more it dries?

11. If there are 5 apples on the counter and you take away 2, how many do you have?

12. Two friends decide to get together; so they start riding bikes towards each other. They plan to meet halfway. Each is riding at 6 MPH. They live 36 miles apart. One of them has a pet carrier pigeon and it starts flying the instant the friends start traveling. The pigeon flies back and forth at 18 MPH between the 2 friends until the friends meet. How far does the pigeon travel?

Good Luck!
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ANSWERS:

4. (3+7)3-7
5. 13112221 (saying that previous line was like: one 'three', one 'one', two 'two's and two 'one's.)
6. Plant three of them in equilateral triangle. Than construct the regular tetrahedron on the basis on three plants and place last one on its top.

Entry no. 3

Three fresh riddles and the solutions to the first tasks!

7. If you turn left glove in-to-out sides, would it match right or left hand?

8. A man must make a statement. If what he says is true, he will be hanged. If what he says is false, he will be shot.

9. How to draw an oval with just one movement of a compass?

Good Luck!
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ANSWERS:

1. 2520 = 5*7*8*9
2. The area is 210, the perimeter 70. Sides: 20, 21, 29.
3. Hah! The construction of such triangle is impossible!

Entry no. 2

4. Try to make a total of 23 using exactly these 4 numbers: 3, 3, 7 and 7. You can use only +, -, and ( ).

5. Find the next term of this sequence:

1
11
21
1211
111221
312211
... ?

6. How can a gardener plant four plants in equal distance one from all another?

Good Luck!
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Entry no. 1

1. What is the smallest value that is divisible by all nine digits?

2. In the right-angled triangle every lenght of side is integer, and the sum of perimeter and the area is 280. Find the sides.

3. What is the area of the triangle that has sides of length 14cm, 6cm and 2(pi)cm ?

Good Luck!
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