Questions tagged [calculation-puzzle]
A puzzle that involves numerical calculations, such as multiplication and addition. Use with the [mathematics] tag.
1,067
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Four ones and four zeros
Which is the smallest natural number that can not be expressed in base 2 with precisely four ones and four zeros using the four basic arithmetic operations, exponentiation, concatenation, brackets, ...
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13
votes
1
answer
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Ernie and the Chance to Save a Beautiful Relationship
I should have smelt a rat when Ernie invited me to an event at the local club rooms, because when I asked why his wife was not attending, he replied that she had another engagement for that night. “I ...
- 13.3k
10
votes
1
answer
239
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Equilibrium of differences
There is a subtraction equation written on the board, with three digits minus three digits, and the first digits both fixed. Alice and Bob need to fill in the remaining 4 digits (A~D below) using 4 ...
- 654
2
votes
0
answers
124
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Multiple Line Lengths around 8 triangles
The image below contains 8 triangles each having side length 6.
Inside each triangles are three numbers indicating lengths of 3 lines that are wrapped around the triangle without gaps.
Numbers range ...
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7
votes
3
answers
663
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1000 digit sum calculation puzzle
I have 7 numbers that add up to the same value as the sum of the base 1000 digits of the product.
Here are the numbers:
86, 203, 296, 395, 401, 407, 913
The first part of the puzzle is to understand ...
- 652
17
votes
1
answer
851
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Time (and a place) for an odd-one-out puzzle
This puzzle is part of the Monthly Topic Challenge #6: Is it really that [time] again?.
It is a tough task to create an 'odd-one-out' type puzzle whose solution lacks any ambiguity at all - it is all ...
- 117k
15
votes
1
answer
1k
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Trust me: you do not want to go down this road with me
Every cell has a digit from 0 to 9 or one of the four operation symbols +, −, ×, and /, signifying addition, subtraction, multiplication, and division respectively.
No digit appears more than once in ...
- 11.3k
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votes
1
answer
152
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Money in a piggy bank [closed]
In the attic of his house a man found an old piggy bank with twelve cents inside. He called two of his friends to come and see the antique piggy bank and asked them to put more money into the piggy ...
- 2,873
6
votes
1
answer
924
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Nifty Nines Impossibility Puzzle
Could someone please provide me the solution to this puzzle:
99 + 9 = 9?
Professor Otto Doppelganger was one of Europe's leading puzzle experts. In the summer of 1899 he invented the Nifty Nines ...
- 71
2
votes
1
answer
239
views
Tile and Error - When Seven Ate Nine
Ok folks, so the three overlapping ellipses form seven curved regions. Your job is to place all seven tiles so that each region has exactly one tile and each ellipse adheres to the corresponding ...
- 2,250
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votes
2
answers
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Create 76 out of 1,2,3,4
You can use +,-,*,/,^,! and sqrt operations (no concatenation) and all numbers must be used once and only once.
for example, 75 can be made by $3×(4!+2-1)$ and $81=(2-1)×3^4$
I've been trying to reach ...
- 123
2
votes
2
answers
370
views
Stuck on hard Kakuro
I‘m stuck on this Kakuro. Does anyone have any hints how to proceed? Thanks!
- 21
16
votes
2
answers
895
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Sergeant Sequence brings in the analysts
This puzzle is part of the Monthly Topic Challenge #5: On-and-onograms
"We've intercepted another message, Chief."
"Good work, Sequence. What does it say? Where is Terne now?"
The ...
- 117k
-4
votes
1
answer
222
views
What is the biggest number you can make with 6 9s?
What is the biggest number you can make with 6 9s?
These are the allowed operators:
Subtraction
Addition
Multiplication
Division
Factorial
Exponents
Square root
Floor and Ceiling functions
Arbitrary ...
- 395
1
vote
2
answers
178
views
Trapped with a number puzzle
A family of your most hated Nggyupnglydown tribe has turned you into a vampire and trapped you in a chamber with a screen and some buttons on it, and you have to enter the code 4, 8, 15, 16, 23, 42 (...
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1
vote
5
answers
356
views
Reviving the Ruins of Number Kingdom
The great wizard Factorial surveyed the empty buildings with an
ever-increasing sense of dread. The staff of recursion he held was
incredibly powerful and could do great damage in the wrong hands. In
...
- 143
22
votes
2
answers
4k
views
Make e using 1, 2, 3, 4, 5, 6, 7, 8, 9
Can you make $e$ with the digits 1, 2, 3, 4, 5, 6, 7, 8, 9?
You can only use the digits once.
The allowed operators are listed beloẉ.
Addition
Subtraction
Multiplication
Division
Square root
...
- 395
2
votes
5
answers
461
views
Make the numbers 1-100 using 1,7,3,4
I made this puzzle myself. As the title says, you must make the numbers 1 to 100 using the numbers 1,7,3,4 - in that order. All numbers must be used. The allowed operators are below:
Addition, ...
- 395
18
votes
2
answers
1k
views
What extra number did I form?
My friend and I are each trying to form the integers from $0$ to $100$ using the numbers $2, 3, 8, 9$. We are only allowed to use the five basic operations: addition, subtraction, multiplication, ...
- 3,660
5
votes
6
answers
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How many digits does $7^{100}$ have?
I'd like to estimate $7^{100}$ without using these new-fangled computers everyone is talking about, but I think I need your help.
Please estimate $7^{100}$ without the use of a computer. My friend ...
- 153
14
votes
15
answers
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The computer can't do anything I couldn't do with pen and paper
If you want to know how much $3^{100}$ is, you can just type it into a computer and it will spit out a really big number. But that is no fun. The task is to estimate $3^{100}$ with some computation ...
- 835
4
votes
1
answer
150
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Can you Avoid the Spear-Wielding Gladiator?
You are trapped in a circular coliseum, and a gladiator with a spear is chasing you. You can't defend yourself, but you can run faster than the gladiator.
You run at 11 feet per second, and the ...
- 41
10
votes
1
answer
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A Pubular Puzzle
Try to make sense of the puzzle below.
Circle1, circle2, circle3, circle4, circle5, circle6 and circle7 have radius r1, r2, r3, r4, r5, r6 and r7 respectively and periferi p1, p2, p3, p4, p5, p6 and ...
- 21.7k
5
votes
2
answers
360
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a six-by-six KenKen
The rules of KenKen are as follows:
You must fill in the numbers 1 through 6, one number per box, in the grid, so each row and each column contains each number exactly once.
Each heavily outlined ...
- 11.3k
4
votes
2
answers
367
views
Dark time in prison
You wake up. It is pitch dark. You don't know where you are. You feel groggy.
The last thing you remember is being in a bar, a sexy young woman appeared out of nowhere, walked straight at you, ...
- 24.9k
2
votes
0
answers
102
views
Three planes fuel tanks for less than halfway around the world - how can one plane make it around the world and what is the minimum fuel tank size?
Inspired by this recent question here is a variation.
Three identical aeroplanes are based on an island with one airport.
Each plane can take fuel to get less than halfway around the world.
Fuel can ...
- 4,166
3
votes
2
answers
285
views
Magic: The Gathering – projecting images
You are in a Magic: The Gathering commander game. It is now your first main phase and you control these permanents:
One Miirym, Sentinel Wyrm: "Whenever another nontoken Dragon enters the ...
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votes
2
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Why are all numbers from 1 to 2N covered by weights with powers of 3?
This is from What's the fewest weights you need to balance any weight from 1 to 40 pounds?
Suppose you want to create a set of weights so that any object with an integer weight from 1 to N pounds ...
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4
votes
1
answer
138
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Find the 3 Item Amounts
Last week the store's receipt printer removed lines randomly from each item amount.
A technician repaired the printer, but now it adds lines randomly to each item amount!
The cashier told me that for ...
- 17.4k
8
votes
2
answers
584
views
A number association puzzle
These 0 to 10 digits are associated with the specific numbers as shown below.
What are the associated numbers for digits 9 and 10? Why?
Bonus: Is there an associated number for 11?
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18
votes
3
answers
743
views
Find the Two Item Amounts
I bought 2 items yesterday and the receipt was incorrect, so I asked the cashier about it.
She told me that
The receipt printer had been acting funny recently.
The total is always correct, but some ...
- 17.4k
2
votes
1
answer
709
views
What is 12 in this same pattern?
7 = 31674ZS
8 = 883011SO
9 = 166037352UR
10 = 434782608W...
6
votes
2
answers
728
views
Compact mathematical expression [closed]
Make a mathematical expression
whose value is equal to 2 that
uses all the digits 0, 1, 2, ... 9
exactly once and uses as few other
mathematical symbols as possible.
- 1,387
4
votes
3
answers
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Some doctors and a lot of hand shakes
At a congress there are some doctors, and everyone shakes a certain number of hands (never more than once with the same person). The doctors can be divided in two groups:
-Group O: the doctors who ...
- 355
0
votes
1
answer
101
views
How many colleagues went to Starbucks?
You go to Starbucks with some colleagues, everybody gets a cappuccino. Every cappuccino contains only coffee and milk (at least some coffee and some milk) and no other ingredients, but everyone has a ...
- 355
15
votes
2
answers
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Patrick and Rachel go to a tennis tournament with 7 other couples
Patrick and Rachel go to a tennis tournament with 7 other couples. Each round is a single's match (1 vs 1). Nobody plays against his/her partner and nobody plays twice against the same player. At the ...
- 355
3
votes
2
answers
153
views
Productive Neighbours
Seven tiles need to be placed so that one is placed in each of the curved "regions" formed by the three circles.
One tile has been placed for you.
Each circle has a corresponding statement. ...
- 2,250
6
votes
1
answer
346
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Problem XXX (Squared) - Number Stile
Happy weekend folks,
The intersections of the three circles divide their interiors into seven "regions"
By complete non-coincidence, we have seven tiles
A "valid" placement is one ...
- 2,250
2
votes
1
answer
123
views
How to fill up the numbers in a set of empty discs drawing a pentagon? The target sum is 10 [duplicate]
Can anyone explain to me the math behind the problem? I want to convert the mathematical solution into an efficient algorithm. The target sum can be any given number. For reference please check the ...
-2
votes
1
answer
204
views
Summa Cum Laude - Tile and Error
For any set X, {X} denotes the sum of its elements. "I divide {A}" means all items in that set are divisors of the sum of A's elements.
Arrange the tiles so that four are in each set and the ...
- 2,250
1
vote
4
answers
188
views
Solve for 69 using only 1 9 9 2 in that order [closed]
You must use all the digits of $1 9 9 2$ in that order to come up with $69$ as the answer.
For example
$ - (1 + \sqrt {9})! + 92 = 68 $
but you must solve for $69$.
2
votes
2
answers
167
views
Twenty (or fewer) questions to solve a three-digit code
In an episode of Odd Squad, the squad are left with five yes/no questions to get a three digit code out of a villain. Luckily for them, they have sufficient questions to guess the first number by ...
- 5,182
4
votes
2
answers
394
views
Determine the highest possible sum of all faces of cube
There is a non-negative integer written on all six faces of a cube. Integers on all possible three common adjacent faces (all faces are adjacent to each other) are multiplied and then they are added. ...
- 1,270
13
votes
2
answers
756
views
Only one such number exists
A 5 digit number ABCDE is divided by 2,3,4,5,6 and gives A,B,C,D,E as the remainders respectively.
Can you find the only possible number?
This was asked in my math exam, I think it would make a good ...
- 1,270
18
votes
3
answers
1k
views
Strategic betting on the world series
Your wealthy father-in-law gives you \$10000 to place a "double-or-nothing" bet on Boston Red Sox in the World Series [1]. In other words, your father-in-law expects to receive \$20000 if ...
- 486
2
votes
1
answer
200
views
A number of ten different digits, divisible by 8, 9, 10, and 11
Each of the digits 0 through 9 is used exactly once to create a ten-digit integer. Find the greatest ten-digit number which uses each digit once and is divisible by 8, 9, 10, and 11.
- 389
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votes
1
answer
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The peculiar inequality [closed]
Let's have the following relation
$\sqrt[3]{\frac{(x+1)^3+x^3}{2}}\lessgtr\frac{2x^2+2x+1}{2x+1}$
where $x$ a positive integer greater than zero. Which inequality is valid?
- 2,873
1
vote
1
answer
151
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Zettler's Encyclopedia
On epiphany 1735, Sir Zettler, who was a great publisher from the old continent, promised to issue a "Great Universal Encyclopedia of Collectible Wisdom". It was meant to be affordable for ...
- 555
11
votes
5
answers
3k
views
Turn the dials until each of the 12 columns add up to 42
I received the wooden puzzle below for Christmas. After playing with it for a while I decided I needed to actually write something down if I was going to solve it. Eventually I just wrote an algorithm ...
- 213
-4
votes
1
answer
129
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Quantity expressed as the difference of two squares
What is the trick you need to use to be able to express the quantity
$(4x^4+8x^3+7x^2+3x+\frac{1}{2})$
as the difference of two squares?
addendum: The answer contains only rational numbers greater ...
- 2,873