You never realized it. Even though I never met, I’m pretty sure of it. You never realized the number 135 is very special. That is because 1 + 3^2 + 5^3 = 135.
The question is: which three other three-digit numbers have this property?
You can check your solution here
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.
Here is a classic:
If 5 rabbits can eat 5 carrots in 5 minutes, how many carrots are eaten by half as many rabbits in half the time?
This kind of problem goes back to at least the middle ages. They have been formulated in many ways: slaves doing work, painters painting walls, cats catching mice, you name it.
You can check your solution here
Mazes are very old and very diverse. I hope to write about mazes in eneral another time, but here is one variation.
Go from 1 the upper left corner to the bottom right corner with the following rules:
1) When you move from one square to the next, add the number in between
2) Every new number must be a prime number
For those of you, a prime number is a number of 2 or more which can only be divided by 1 and by itself. Thus 2, 3, 5 and so on are prime numbers, but 4, 6 and 9 are not.
I found this type of puzzle in one of the old Dutch math olympiads.
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.
The illustration shows an old fashioned analog clock.
Usings two straight lines, in how many parts can you divide it so that the digits on all parts have an identical sum?
I found this puzzle on aplusclick.com as a former math olympiad problem.
I would like to encourage you to solve this puzzle on your own. It will increase your self confidence, while looking up the answer will lower your self esteenm.
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 solutions – 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.
1) 3×3
Every row and column adds up to 50
Complete the square with the indicated numbers – those who have been given are already crossed out for you.
2) 4×4
Every row and column adds up to 50
3) 5×5
Every row and column adds up to 100.
This type of puzzle was published in Cijfervaria, a publication of Sanders Puzzelboeken. As I write this, they just published issue 5. Though I missed issue 4, I see they regularly publish Soduko variants, Binairo, Triairo, hitori, and battle ship.
You can check your solution here, here and
here.
Did you know…
Learning new tasks saves brain cells – even if these tasks are more or less similar to already known tasks.
Using exactly four fours, create the numbers 0-30. You may use the usual mathematical operands, but not squaring, as this requires a number 2. You may use brackets.
Example: (4+4)-(4+4)=0
As always, please don’t publish your solutions. Solutions can be found after 1-2 weeks on the solution page for those who want to check their solutions, or for those who are really stuck.
But scrolling is much easier, and really spoils the fun for others.
I am very much interested in your solution times, and I welcome your remarks and criticisms. Pointing out alternative solutions is also welcome, as they point out possible problems in the brain teasers.
If you are puzzled, we have a solution for you.
This puzzle has a long history. When I still was a teenager, my father challenged me to make all numbers 0-20 using the digit 4 exactly 4 times. Recently I shared this puzzle with some fellow consultants. Kees Krol arrived at the office one morning and announced he had extended the range all the way to 30. 🙂
IF
8 x 2 = 46416
6 + 3 = 23618
15 : 3 = 513545
9 – 3 = 38127
Then what is :
12 x 4 =?
I am very much interested in your solution times, and you are welcome to make remarks, and discuss alternatives. Pointing out alternative solutions is also welcome, as they point out possible problems in the brain teasers, but please dont mention solutions and leave others the fun to solve them too.
If you are puzzled, we have a solution for you.
If you are puzzled, we have a solution for you.
I would like to thank Kees Krol again for coming up with this one.
As always, please don’t publish your solutions. Solutions can be found after 1-2 weeks on the solution page for those who want to check their solutions, or for those who are really stuck.
But scrolling is much easier, and really spoils the fun for others.
1)Make 21*
No, it’s not the card game.
The puzzle is can simply be formulated: make 21 using the numbers 1, 5, 6 and 7 once each, by combining them with the operators + – * / and the ().
The word ‘numbers’ is on purpose, i do mean numbers and not digits. And there are no tricks involved such as turning digits around, making a 9 from the 6.
Kees Krol also brought this puzzle to my attention, again: Thank you, Kees!
You can check your solution
justpuzzles 