# Questions tagged [calculation-puzzle]

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

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152 views

### Open the third door!

I was wandering in an abandoned house. When I went down to the basement I found three doors. All three doors have a triangle painted on them, two of them with a number outside the triangle, these ...
216 views

### Keys, codes and patterns

My flatmate always forgets his key, so now we have installed a small locker outside the room where a spare is located. So that my flatmates doesn't forget the code we made this small riddle for him, ...
415 views
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### Recipe for diced shark fin

How may the following shark-fin-shaped Goal distribution be cooked up with 44 ingredients in a roll recipe R based on the roll sum of two 6-sided dice with non-standard allotments of dots? Goal: ...
12k views

### I don't know the two numbers… but now I do

Two perfect logicians, Summer and Proctor, are told that integers $x$ and $y$ have been chosen such that $1 < x < y$ and $x+y < 100$. Summer is given the value $x+y$ and Proctor is given the ...
6k views

### Find the missing number (triangle)

Find the missing number (triangle) Options: 9 8 7 10 Please write the logic also.
94 views

### Circle puzzle critical startegy [closed]

Answer it with the formula for the three circle puzzle.
167 views

### Reverse Engineering Computer Formula

A computer uses an unknown formula to create a 4 digit Output using specific Input. Here are 3 examples: Input = 20066 : 020470 : 47 : 1 : 322267 Output = 0927 Input = 20066 : 020470 : 46 : ...
134 views

### How to find numbers in the puzzle square box [closed]

I was trying to find answers for below diagram.I simplified with four equation as a+b = 25 c-d = 35 a+c = 50 b+d = 60 then I got ...
425 views

### Something I loved the most

Below are some puzzles you need to solve to make a 4 letter word. 1. 105 35 315 ? 2. I am the most important element in your surrounding. I was found by a Scottish physician. Who am I? 3. I am ...
245 views

### Can you fill in the missing number?

Try to figure out what number might be missing inside circle (sorry for bad drawing :P ) . All the best :) Hint #1
622 views

### 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 ...
712 views

### Place the numbers 1-7 in the squares so that each row and columns adds up to the same total

A F B D E C G A+B+C = B+D+E = F+E+G Numbers 1,2,3,4,5,6,7
126 views

How should the numbers be filled in in this arithmetic grid?
543 views

### Analogy with Number

The given analogy is 343 : 989 :: x : 669 What is x? 223 332 333 233
173 views

### NineFind - Which 9 Numbers Are Correct?

Text Version: ...
196 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 :
149 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 $a + b + c$
204 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 ...
210 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.
172 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:
1k 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 ...
115 views

### A Tribute to Countdown

Leave empty or put a multiplier, divider, adder or subtractor in the boxes: For example:
137 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 ...
121 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.
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?
394 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? ...
433 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 ...
211 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. $$\text{London = 6800}$$ $$\text{Paris = 9248}$$ $$\text{Seoul = 9100}$$ $$\text{Tokyo = 7500}$$...
376 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 ...
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 ...
21k 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 ...
221 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
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 ...
546 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.
210 views

### Find the missing number from the pyramid

? 1 3 3 3 9 9 3 1 9 Find the missing number in the pyramid?
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 ...
658 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:
274 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 ...
322 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 ...
394 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 ...
98 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 ...
462 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 ...
118 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 ...
628 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 $2000$ ...
562 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.
426 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 ...
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?
157 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.