Bongard problem 12

March 1, 2019Bongard problemsTeun Spaans

Which rule satisfies the 6 figures on the left but is obeyed by none of the 6 figures on the right?
1)Bongard problem 12^**/*****

In 1967 the Russian scientist M.M. Bongard published a book containing 100 problems. Each problem consists of 12 small boxes: six boxes on the left and six on the right. Each of the six boxes on the left conform to a certain rule. Each and every box on the right contradicts this rule. Your task, of course, is to figure out the rule.

You can check your solution here

You can find more Bongard problems here on this site and at Harry Foundalis’ site.

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Three squares

February 15, 2019Arithmetic, NumbersTeun Spaans

What number goes to the question mark?

1) Nr 1^**/*****

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2) Nr 2^**/*****

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3) Nr 3^**/*****

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Bongard problem 11

February 1, 2019Bongard problemsTeun Spaans

Which rule satisfies the 6 figures on the left but is obeyed by none of the 6 figures on the right?
1)Bongard problem 11^**/*****

You can check your solution here

You can find more Bongard problems here on this site and at Harry Foundalis’ site.

1 to 9

January 18, 2019ArithmeticTeun Spaans

1 to 9^**/*****

Fill the grid with each of the numbers 1 to 9 exactly once :

New puzzles are published twice a month on Fridays.

You can check your solution here

Bongard problem 10

January 4, 2019Bongard problemsTeun Spaans

Which rule satisfies the 6 figures on the left but is obeyed by none of the 6 figures on the right?
1)Bongard problem 10^***/*****

You can check your solution here

You can find more Bongard problems here on this site and at Harry Foundalis’ site.

2019

January 1, 2019ArithmeticBrainteasersTeun Spaans

1) Make 2019 (1)^**/*****
Take the series 1,2,3,4,5, etc. Insert + and – signs in between the numbers to make 2019. Do not use brackets. What is the shortest series?

2) Make 2019 (2)^***/*****
Take the digits, 0-9. Keep them in exactly this ascending sequence and combine them wit +, -, *, /, ^, brackets and/or ! to make 2019.

3) Make 2019 (3)^***/*****
Take the digits, 0-9. Order them in descending sequence (9, 8, 7, down till 0) and combine them with +, -, *, /, ^, brackets and/or ! to make 2019.

4) The digits 2, 0, 1, and 9^***/*****
The year 2019 is made up of the digits 2,0,1 and 9. Combine them with all mathematical and arithmetic operators to make every number 0-20. For example: 0*1*2*9=0.

5) The digits 2, 0, 1, and 9^***/*****
The 9 is the largest digit in “2019”. It is the square of the sum of the three other digits (9 = (2+0+1)^2). What is the next year when the largeest digit is euqal to the square of the other three digits?

You can check your solutions here

The end of 2018

December 28, 2018ArithmeticTeun Spaans

1) 2, 0, 1, 8^**/*****
In the days between Christmas and old year many people have a few days off. Ideal to solve some puzzles.
Use the digits 2, 0, 1, and 8 to make all the numbers 0 till 20 by combining these digits with brackets and / or all arithmetical operations.

You can check your solution here

Billy’s Big Christmas Party

December 21, 2018Arithmetic, Recreational mathematics, Spatial reasoningBrainteasers, Christmas, PuzzlesTeun Spaans

Billy was delighted to have gained entry to the Big Christmas Party in the neighbouring village. There were stalls and booths littered throughout the hall.

1) The apple pie stall^**/*****
The first stall he walked to showed delicious steaming hot pieces of apple pie on display. Several other kids had gathered in front of it.
A sign read:
4 and 7 give 33
3 and 2 give 5
8 and 5 give 39
A middle aged lady behind the stall held up two numbers: 6 and 3.
“This woman must be the wife of the math teacher,” he whispered to his neighbour.
The lady must have overheard him, because she laughed:
“Young man, I am the math teacher.”
But she was quickly satisfied when Billy quickly figured out the correct answer, collected his piece of apple pie and walked to the second stall.

You can check your solution here

2) The hot chestnuts stall^****/*****
The second stall displayed dishes of chestnuts filled with had chestnuts. A man was roasting the chestnuts on a small coal fire and serving them with several sauces.
A sign displayed some calculations:
11 + 11 = 8
12 + 59 = 18
18 + 47 = 16
23 + 39 = 16
He held up two numbers for the children in front of his table: 22 and 45.
Slightly softer than the previous time, Billy whispered to the girl besides him:
“Do they have two math teachers here?”
The girl looked at him saying:
“Did you ask if we have two math teachers here?”
The man heard it and laughed: “No, I’m the Arts teacher.”
Billy quickly grasped the problem and found the sum of 22 and 45.

You can check your solution here

3) The mince pies^****/*****
The third stall displayed a lovely looking plate with mince pies.
A piece of cardboard listed:
5 and 6 give 6
3 nd 7 give 7
7 and 8 give 8
She held up two cards showing 4 and 12. “What number do they give?” she asked. “I’ll tell you in advance the answer is not 12.”
To prevent him from asking, the girl besides him told him:
“No, she doesnt teach math. She teaches English.”

You can check your solution here

Numbers

December 14, 2018ArithmeticBrainteaserTeun Spaans

1) Three blocks of numbers^***/*****

You can check your solution here

The animals in my house

December 7, 2018Arithmetic, NumbersTeun Spaans

Animals^*/*****

In our house, we have more than two animals. All the animals in our house are dogs, except for two. All the animals in our house are cats, except for two. All the animals in our house are mice, except for two.