1) Number square*
Find the missing number:
solution: Here)
Tag Archives: puzzle
What comes next?
What number comes next in the following sequence?
56789
51317
548
…
You can check your solution here
Billy and the christmas party
Billy desparately wanted to go to the christmas party in the neighbouring village. All the pretty girls from all over the neighbourhood would be there and would be giving kisses to anyone under the mistletoe. And he sure would be there right under the mistletoe as often as he could!
Because he was late, he decided to take a shortcut through the old railway tunnel. It was a straight tunnel and he had an excellent view. When he was still 32 meters from the middle of the tunnel, he heard a train coming up from behind. It was still as far away from the entrance of the tunnel, as the tunnel was long. He immediately ran back and made it with just a meter to spare!
If he had ran to the exit ahead of him with the same speed, the train would have caught him 20 meters before the exit of the tunnel.
Somehow the train driver must not have seen him, maybe by the darkness in the tunnel, as it drove on at the same constant speed all the time.
How long is the tunnel?
What the trains speed was? Oh well, I’m sure little Billy told me, but you know, old age and memory and such – I have completely forgotten. Certainly you are so good you can do without?
Formal disclaimer: Never use an old railway tunnel. There are two possibilities: either the railtrack is in use or it is not. If the track is in use, you may be caught by a scheduled or an extra unscheduled train by surprise. If the track is no longer in use, the tunnel is not maintained and may be be liable to cave in.
You can check your solution here
You are welcome to remark on the puzzle: its wording, style, level of difficulty. I love to read your solution times. Please do not spoil the fun for others by listing the solution. Solutions will be posted after one or more weeks.
Two watches
I started two watches at the same time and found that one went two minutes an hour too slow and the other one minute an hour too fast, so that when I looked at them again the faster one was exactly one hour ahead. Can you figure out from from the picture at what time before noon the watches must have started?
This problem was first posted by American puzzle genius Sam Loyd. It was incorporated into his Cyclopedia of Puzzles on page 30.
You can check your solution here
You are welcome to remark on the quirks in the puzzle, and i especially welcome your solution times. The solutions itself will be published after one week.
Five triangles
Imagine a right triangle (formerly called a rectangled triangle). One side adjacent to the right angle is twice as long as the other. You will not find it very difficult to construct a square from 4 of these triangles.
But is it possible to construct a square from 5 of these triangles? And from 6? From 7?
These problems are derived from ‘doordenkertje’ 12 in the November 1969 issue of ‘Pythagoras’, a Dutch magazine in recreational mathematics. You will need some elementary geometry knowledge to solve this problem.
You can check your solution here
Pattern code square and circle
Four combinations of a square and a circle have been labelled with a three letter code. What code should the combination in the middle have?
You can check your solution here
10 glasses
There are 5 filled and five empty glasses in a row:
A) Can you move 4 glasses in such a way that full and empty glasses alternate?
B) Can you move just 2 glasses so that full and empty glasses alternate?
I invite you to comment on the puzzle, but please do not give the solution. The solution will be given later.
You can check your solution here
colour grid (2)
Usually I construct my puzzles in such a way that the puzzles can be made and solved by those who are colour blind. That is alas not the case with this weeks brainteaser, for which I apologize.
The question is: what colour should go into the white square with the question mark?
You can check your solution at here
Lines and spheres
Color grid (1)
What number goes into the cell with the question mark?
1) Color grid*
You can check your solution at here
Please try to solve the puzzles on your own: your self confidence will grow. You are welcome to remark on the puzzles, and I love it when you comment variations, state wether they are too easy or too difficult, or simply your solution times. Please do not state the soultions – it spoils the fun for others. I usually make the solution available after one or two weeks through a link, which allows readers to check the solution without the temptation to scroll down a few lines before having a go at it themselves.
You can find more puzzles of this type in one of our free or paid upcoming e-books on Logic puzzles.
justpuzzles 