Questions tagged [calculation-puzzle]

A puzzle that involves numerical calculations, such as multiplication and addition.

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2
votes
2answers
17 views

Analogy with Number

The given analogy is 343 : 989 :: x : 669 What is x? 223 332 333 233
2
votes
1answer
51 views

Find missing number

In below grid there are 2 numbers missing fill it with appropriate number . Text version: 69 10 13 192 ? 45 279 64 ? Hint :
3
votes
1answer
103 views

Math Puzzle: Totaling up A,B, C [closed]

We know the following about the numbers $a$, $b$ and $c$: $$(a+b)^2=9,\quad(b+c)^2=25, \quad(a+c)^2=81$$ If $a + b + c ≥ 1$, determine the number of possible values for $a + b + c$
14
votes
1answer
433 views
+50

Shots, shots, shots, shots!

Once in a while I go out for a drink to my favourite bar. Normally is just drink a beer, eat some snacks and have a good time with my three friends. But last night I wanted to do some shots. The ...
3
votes
0answers
182 views

3 x 3 Grid Square Problem

For a question that I need to answer, we have to show that there is only one arrangement for which, in a 3 x 3 grid in which the numbers from 1 to 9 are placed and 5 is the centre number, the sum of ...
5
votes
1answer
172 views

Find the missing 2 number inside inner circle

This puzzle is made by me. In the below diagram you can see there are two missing numbers; you need to fill them with the appropriate numbers.
4
votes
1answer
150 views

What is the missing number in this grid composed by 25 values?

Well, I have created a simple table with 25 values, inside it, all the data is readable, except for one that is hidden. Can you guess it? The table:
-1
votes
0answers
94 views

Please solve this interesting riddle [closed]

Hi There, Please help in solving this puzzle.... Thank You!
5
votes
1answer
834 views

How to programmatically solve math puzzle

I have this puzzle and I want to solve by code. I wrote simple code trying to brute force but it fail in one condition https://dotnetfiddle.net/cJyu3w Anyone know of a link or source how to solve ...
6
votes
1answer
110 views

A Tribute to Countdown

Leave empty or put a multiplier, divider, adder or subtractor in the boxes: For example:
6
votes
2answers
128 views

Squared, what is in the post-scriptum?

Just received an invitation from a fellow mathematician for a party. The invitation is quite clear: where I need to be at what time is clearly said in the invitation, but at the bottom of the ...
1
vote
0answers
110 views

Find the missing number in the series

Numbers in the series: 4,12,14,16, ?, 25 Please help me find the missing number in the series above. I have already tried with different sequences but unable to solve this. Thanks.
132
votes
8answers
34k views

How can 64 = 65?

Here is a interesting picture with two arrangements of four shapes. How can they make a different area with the same shapes?
9
votes
1answer
388 views

Given these numbers, find the hidden word

Given this sorted list of 33 numbers, is it in your power to find the riddle they are hiding and figure out the secret word? ...
11
votes
1answer
428 views

Can you decipher these ancient numerals?

This stone was found at the foot of an ancient door. This old note with some mathematical relationships was discovered nearby. Can you use this information to figure out what number each of the 9 ...
8
votes
1answer
206 views

Six cities. What's the missing number?

Six cities are listed below. For five of them, their numerical value is given. Find the missing number. $$\text{London = 6800}$$ $$\text{Paris = 9248}$$ $$\text{Seoul = 9100}$$ $$\text{Tokyo = 7500}$$...
1
vote
3answers
357 views

3 bags of coins, find which bag contains fake coins, doing only 1 weighing

Probably a very easy puzzle for you guys; my point is more a mathematical one. FYI, it was shown in an episode of Columbo. You have 3 bags of coins. Each bag contains 50 identical coins. Two bags ...
11
votes
7answers
3k views

How should they divide the money?

Three friends go on a picnic. John brings a loaf of sliced bread. Raj brings sliced tomatoes and Von brings a package of sliced cheese. They make sandwiches and eat them. John’s sandwich has 2 ...
15
votes
3answers
20k views

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 40 pounds can be balanced on a two-sided scale by placing a certain combination of these weights onto ...
7
votes
1answer
203 views

Picture-Puzzle. Find the number!

Make sense out of this picture below and find the two-digit number! Note: Pay attention to everything except the rounded rectangles
6
votes
4answers
1k views

Quick way to find the square root of 123.45654321?

If $n^2= 123.45654321$, then what will be the exact value of $n$? Is there a neat/efficient way to solve this without using the long division method? Since this is a GRE question, I believe there ...
3
votes
1answer
526 views

Challenge on ASCII Codes

My friend shared a challenge puzzle with me but I don't have any idea on this? I believe that it's related to ascii characters.
10
votes
2answers
193 views

Find the missing number from the pyramid

? 1 3 3 3 9 9 3 1 9 Find the missing number in the pyramid?
5
votes
3answers
9k views

Finding Day Puzzles

When the day after tomorrow becomes yesterday, the day which would then be today will be as far from Sunday as the day which is yesterday when it's two days after that day's tomorrow. What day of the ...
16
votes
2answers
651 views

16 number puzzles on a blackboard

I have left you some number puzzles on the blackboard. Solve them and let me know what they spell. Hint:
10
votes
1answer
272 views

Catching the thief before it's too late

London, 17:15. Inspector Arbor wasn't quite happy with the current situation. Normally, he would have enjoyed this sunny Saturday outside at the Park but now wasn't the time for that. Valuable ...
6
votes
4answers
316 views

9 8 7 6 5 4 3 2 1 = 0 and 1 2 3 4 5 6 7 8 9 = 0

There are many number sequence puzzles on this site. I acknowledge them all. Martin Gardner introduced the puzzle with the 9 digit sequence with math operations, reaching 100 as below An old ...
1
vote
5answers
389 views

Multiple XOR operations

Find $8$ distinct $8$-bit numbers, each with $4$ bits set to one, such that the cumulative XOR of these bytes is $10101010$. I imagine there are multiple answers, so the first correct answer wins the ...
-2
votes
2answers
95 views

Which number is the largest in this division case? [closed]

I came across this puzzling question in a coaching school exercise book for children preparing for selective high school enrolment test. I can't figure out the answer and suspect something was wrong ...
15
votes
2answers
461 views

Cloudy with a chance of meatballs

I discovered that I can control the local weather, depending on what color shirt and hat I wear at a given location. My home country of Flanmanistan has hired me to go back and do drought and famine ...
1
vote
1answer
116 views

Banknotes recalling [closed]

Last year the inhabitants of Elfland (which are -of course- Elfs) had a referendum and decided to stop using barter and to adopt their own currency (the Elfcoin). On January 1st, 2020 the central ...
10
votes
1answer
622 views

Three shy fairies performing two thousand times

Three shy fairies participate in a dance competition. Since they are shy they don't want to be seen by anyone except for the five judges of the competition. The competition is composed of $2000$ ...
3
votes
3answers
532 views

Number puzzle i really need help with

I found this puzzle in a VRChat world. Its a 6 number puzzle, and I need to know the value of “? ? ? ? ? ?”. I also need to know the number.
7
votes
1answer
419 views

Living in prime years

A human was born somewhere in interval of [1;1920] A.D. They lived exactly 100 years. They lived through more years that were prime numbers than any other human (of the same lifespan) who was born in ...
5
votes
4answers
4k views

Men digging holes

Suppose 9 men take 9 hours to dig 9 holes in the ground. (a) How many hours would it take 3 men to dig 3 holes? (b) How many men would it take to dig 54 holes in 54 hours?
3
votes
1answer
155 views

Guess the missing digits [duplicate]

Can you guess the missing digits in the following multiplication? ??? x 3? = ???? Digits from 1 to 9 appear exactly once each. The goal is to solve it with as little calculation as possible.
-1
votes
1answer
2k views

How to solve Rubik's Cube using mathematical formulas? [closed]

I am trying to solve Rubik's Cube, but it took one month for me when I started. Are there any mathematical formulas, rules and tips for solving Rubik's Cube in less time (i.e. minutes)?
2
votes
1answer
189 views

Visual calculation puzzle

Below are some objects and numbers. Try figure out what they represent and finally replace the question mark.
5
votes
1answer
229 views

Why do I celebrate later? (still 13,37 years)

A very little time ago, just a bit ago one may say, people started partying. Some even went out of their houses to do so… crazy thing, IMHO. Anyway, I don't, I'll start partying in 4886 days.¹ Why do ...
9
votes
3answers
2k views

$\tau$ is greatest! $\tau$ is all (from 1 to 20)

(This is basically an extension of $\pi$ Day puzzle one to twenty) $\tau$ is greater than $\pi$ and $\tau>\pi$. Create the numbers from $1$ to $20$ using only: Tau ($\tau$, equivalent to $2\pi$) ...
-4
votes
3answers
223 views

Ten, nine, eight, seven, six, five, four, three, two, one

Some of us already did, and some of us are going to end the years with the word "teen" in it soon, for another 94 years. So let me ask the question: How many distinct numbers can you produce with ...
67
votes
12answers
55k views

A camel transporting bananas

A somewhat well-known puzzle is described as such: You have a pile of 3,000 bananas. You wish to transport them to a place 1,000 miles away on the back of a camel; however, the camel can only carry ...
9
votes
1answer
391 views

Four dice puzzle: What's the best throw?

This continues Damiano's puzzle "Four dice puzzle: 2,2,4,5" Damiano keeps throwing his four dice. After a lot of throwing and thinking and working, he has determined for every throw $a,b,c,d$ of his ...
8
votes
2answers
669 views

Four dice puzzle: 2,2,4,5

Damiano has thrown four dice and the numbers 2, 2, 4, 5 showed up on top. Damiano asks himself: What is the smallest positive integer that cannot be generated with these four numbers according to ...
72
votes
15answers
14k views

Making π from 1 2 3 4 5 6 7 8 9

There have been two other questions here and here that are similar to this one, but this changes the rules up a little. Your job is to approximate $\pi$ using the sequence of digits (in order): 1 2 ...
3
votes
3answers
622 views

What's the missing number?

$\begin{array}{ccc}6&7&4\\ 4&11&14\\ 13&2&11\\ 6&8&1\\ 15&3&?\end{array}$ Own attempt at building a puzzle, find the missing number.
8
votes
1answer
248 views

Maximizing Product of Selected Cards

Jennifer is playing a game. The Ace through King of spades are taken from a standard playing deck and laid out facedown on the table. At any time, Jennifer can select two cards and reveal them, and ...
5
votes
1answer
220 views

Two cards which product is not a square

There are 100 cards on a table numbered 1,2,...,100. What is the maximum number of cards, which can be selected such that no two cards have a product, which is a perfect square? Example: you cannot ...
1
vote
1answer
90 views

Date from 2 wooden cube puzzle [duplicate]

In an interview the interviewer asked me a question based on date. Suppose in a office, at the manager's desk there are 2 wooden cubes to show the date of month, every day the manager sets the cubes ...
0
votes
1answer
210 views

“When the Romans counted the entirety of their whole army, their sum was greater than the value of this.” [closed]

I came across this site and you all seem really smart so I was possibly hoping you could help me. I have this puzzle and I can't work it out, does anyone has a clue or answer? When the Romans ...

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