Questions tagged [calculation-puzzle]

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

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7
votes
3answers
406 views

Writing differences on a blackboard

The numbers 25 and 36 are written on a blackboard. At each turn, a player writes on the blackboard the (positive) difference between two numbers already on the blackboard, if this number does not ...
3
votes
2answers
151 views

The fantastic matrix

Here's another question that I have been asked in an interview lately. Let $M$ be an $n × n$ matrix whose values are $”+”$ and $”-”$. M is called fantastic if it is possible to make all it's values $”...
1
vote
2answers
87 views

Fill two dimensional list by meeting given conditions

Suppose you have a 2D array - a list that exits in both x and y axis - which is 4 x 4, and you need to fill the table by putting numbers in it obeying following restrictions. Each cell is able ...
3
votes
1answer
261 views

Infinite dials to reset ever?

I have an infinite number of dials with red needles that rotate $n\in\mathbb{Z^+}$ times every second. They all start pointing North. Will they simultaneously all point North ever again?
4
votes
2answers
439 views

How to make 18 from 1, 3, 4, 8

This question was on my sister's 5th-grade homework, practicing order of operations. It was to make 18, using the numbers 1, 3, 4, 8 and the operations +, -, and *. The instructions imply using each ...
7
votes
3answers
662 views

Homeostasis logic/math problem

I'm trying to derive a generic formula for a programming algorithm. I might be overthinking this or underthinking it... we'll see. Each of the triangles below represents a container. Each container ...
4
votes
2answers
224 views

Digital Font Puzzle. One easy the other may be not

In the Digital Font shown below, each letter is made up of line segments. For example letter A has 6, B has 7, C has 4 segments and so on. Question 1 ( Easy) Which english number, when spelled out ...
3
votes
1answer
314 views

Albrecht Durer Inspired Magic Square

A magic square is an n-dimensional matrix in which each row, column, and main diagonal sums to the same 'magic number' (denoted by s). A normal magic square uses each of the numbers from 1 to n ...
-4
votes
2answers
179 views

Jug problem with 3 jugs [3, 4, 5] [closed]

How do you get 10 and 11 liters from 3, 4, and 5 liter jugs?
24
votes
4answers
11k views

The largest integer made of 1,2,3,4

What is the largest integer $A$ that can be produced from the four digits $1,2,3,4$ subject to the following rules? Each of the digits $1,2,3,4$ is used exactly once. Juxtaposition of digits is ...
-6
votes
1answer
103 views

The master puzzle

Take any angle in a circle Divide that respective angle in equal proportions up to infinity intervals . Then apply a pattern that I had given below . The numbers you obtain after doing so should be ...
29
votes
10answers
9k views

Using only 1s, make 29 with the minimum number of digits

Use the minimum number of ones to make 29. Here is the list of operations permitted: "Standard" operations, such as: $x+y$, $x-y$, $x\times y$, $x\div y$ Negation: $-x$ Exponentiation of two numbers:...
15
votes
1answer
963 views

One beer too many

You're standing outside your apartment building after a late night out, with perhaps one beer too many, and you realize you have completely forgotten the code to get in. Luckily, you're a mathematical ...
4
votes
10answers
16k views

How to prove that this man has a profit of 20 and not 10?

This is not actually a puzzle per se, but I'm asking for an explanation about the puzzle's answer. The puzzle goes like this: A man bought a goat for 60. He then sold it for 70. Later, he bought ...
-3
votes
1answer
238 views

Word Puzzle: Find The Maximum Words (+Mystery Clue)

Similar to the heart of this, but with different rules, I have developed a new word puzzle. Partial answers which answer part of it correctly will be upvoted! Your objective is to find the maximum ...
8
votes
2answers
374 views

Houses and Telephone #s

There are 16 houses consecutively numbered 1-16. All houses have 7-digit telephone numbers, numbered consecutively, in the same order. For example, if house #3's phone number is 1111111, house #4 will ...
4
votes
1answer
223 views

systematic number removal [duplicate]

The whole, natural numbers 1 through 50 are written on a board. The following operation is performed 49 times: select any two of the numbers on the board and write the absolute value of their ...
4
votes
1answer
452 views

Analyzing Single-Elimination Tournaments

I know there are many questions/answers about single elimination tournaments out there, but I wanted to approach this question in a more holistic way. For a single-elimination tournament with N ...
5
votes
1answer
159 views

What is next in the number sequence?

Two and two is four, But three and three is nine; Four and four is eighty, But five and five is none. What is the next line in the sequence?
3
votes
3answers
298 views

Is it possible to methodically find the total of ways to read a given phrase making a stack? [closed]

I have been going in circles for a few days now with this word-search puzzle and I still cannot find a clever solution to the problem. Is there a systematic approach that doesn't involve guessing? The ...
2
votes
4answers
392 views

The Building, the Elevator and the Milkwoman

A building has $10$ stories ($i=1, 2, \ldots, 10$, where $i=0$ is the ground floor). Each of those stories have $4$ apartments. Inside each apartment there is a married couple. The ground floor, $i=0$,...
12
votes
8answers
3k views

Create all numbers from 1-100 using 1,3,3,6

Create all the numbers from $1$ to $100$ using the numbers $1$,$3$,$3$, and $6$. You can only use each number once, except for the $3$, of which you have two. You can use addition ($x+y$), ...
1
vote
5answers
272 views

Create all numbers from 1-100 by using 1,3,3,7

Create all the numbers from $1$ to $100$ using the numbers $1,$$3,$$3,$ and $7.$ You can only use each number once, except for the $3,$ of which you have two. You can use addition $(x+y),$ ...
8
votes
3answers
362 views

A puzzle in kindergarten's book

I found the following puzzle in a kindergarten book: Can anyone give a clear explanation as to what the answer is and why? The first time I tried to solve it I got an answer of 6, by noting that the ...
2
votes
5answers
388 views

Find the missing number in grid

When I doing the IQ paper last Sunday, I found an interesting question. Using that I made a different puzzle. Hint 01: Hint 02: Hint 03: Hint 04: Text version: 25 13 43 35 66 53 45 -- 63 55 ...
2
votes
0answers
98 views

Write $\sqrt{5}$ as sums of powers of $1 + \sqrt{2}$? [closed]

The number $A = 1 + \sqrt{2}$ solve the equation $A^2 = 1 + 2 \sqrt{2} + 2 = 1+2A$. We also have that $$0 < \dots < A^{-2} < A^{-1} < 1 < A < A^2 < \dots $$ The powers are in ...
3
votes
4answers
429 views

What will be the next term in this mathematical sequence?

What will be next in this series? $$0, 6, 24, 60, 120, 210, ...$$ I've tried it and noticed that the numbers are multiples of six. But I couldn't make a relation between them.
9
votes
2answers
528 views

Who gets more money?

There are two people eating bread. One of them has 5 loaves of bread; the other one has 3. They invited a third person to eat with them. They ate all 8 loaves of bread, and out of appreciation he gave ...
2
votes
1answer
696 views

Help solving a math puzzle table

I am struggling to find the answer. Here is the source: math logic puzzle phone app.
15
votes
3answers
2k views

The Pie-Maker's Son

Preface: There's a lot of background story here. Most of it is just for fun but there are definitely clues sprinkled throughout. If you want the strict puzzle, skip on down to the bottom. For many ...
4
votes
2answers
331 views

5 Digit Code Puzzle

We have a 5 digit code, any place can take 1 2 or 3. How do I find where the 2 is placed (if placed) knowing this criteria? 1) If the 1st digit is not a 3 then the 2nd is. 2) If the 1st ...
3
votes
1answer
113 views

How many possibilities are there for the buried treasure?

You have discovered a map to some buried treasure on an island the shape of a circle. The map has 9 markers which represent posts situated on the edges of the island. The 9 posts are located; North, ...
5
votes
7answers
1k views

9sums - a logical deduction puzzle

Each set of minuses contains an integer in the range [1,5]. The given numbers are the sum of the surrounding 4 numbers. --- --- --- --- 13 14 11 --- --- --- --- 11 ...
3
votes
2answers
122 views

Simple and intriguing

Five friends are sharing information about the marbles they have attempting to derive the total amount of marbles they own without disclosing to others the amount each own. They decide to do it by ...
1
vote
2answers
598 views

What is the next number in the given series?

I know that next number questions are not popular here, but this one is tough and I couldn't figure out the pattern. To give an idea one of the questions had a pattern of Prime(Fib(n)). So this is ...
2
votes
1answer
98 views

14sums - the diamond standard

My initial question had lots of answers, and my second had too many constraints. So, I have removed some constraints and added another. Same rules as before, but we are now using $[0,6]\cap\mathbb{Z}$....
12
votes
4answers
4k views

Doubling/tripling puzzle: make 1 from 1536 in as few steps as possible

You start with the number 1536. Your mission is to get to 1 in as few steps as possible. At each step, you may either multiply or divide the number you have, by either 2 or 3; but, only if the result ...
-1
votes
6answers
746 views

How do I make 76 using only the numbers 2,0,1,9? [closed]

I must use each number 2,0,1,9 (only once) to come up with an answer of 76
1
vote
0answers
43 views

Sequence puzzle in rows [duplicate]

The below is a number puzzle. It should be read left to right, top to bottom. Question 1: What is the next two rows of numbers? Question 2: How was this reached?
7
votes
6answers
2k views

Through which number we can remove the question mark?

I'm trying to solve this puzzle but so much confused and can't understand even.Please help me to solve this puzzle and also explain briefly.
5
votes
1answer
131 views

21sums - more constraints

My initial question had lots of answers, as we can practically choose the middle square to be anything we want, and work outwards to the exterior edges, with the corners providing the flexibility ...
10
votes
1answer
2k views

Which two numbers replaces the question mark?

I was solving some number puzzles. I am finding difficulty in solving this puzzle: which two numbers will replace the question marks? I need answer with explanation.
5
votes
5answers
4k views

A Set of Water Jug Challenges

You've probably heard about challenges with water jugs, so why not try a few? Use 3- and 5- liter jugs to get 4 liters. Use 5- and 7- liter jugs to get 4 liters. This one's different. How many ...
7
votes
2answers
382 views

Fuzzy the Fuzzball

Fuzzy the fuzzball was very sad. He had lost his fuzz. Everyone knew if you lost your Fuzz you could no longer be a fuzzball. Fuzzy went to this friend Frizzy and shared his dilemma. "Don't worry, ...
7
votes
2answers
958 views

What date can it be?

To save money, a meticulous person had a oddly unique way of splurging money. Each day the person would splurge an amount equal to the month-digits + day dollars. So for the first of April it would ...
10
votes
3answers
646 views

Finding the Dr. Bronowski's number

All credit for this problem goes to Dr. J. Bronowski. Find the least positive integer such that moving the leading digit to the end produces a new integer one and a half times the original.
14
votes
11answers
22k views

Find out the correct number

Find out the correct number to replace the question mark. Source: Beijing Aidi International School summer test (2018-08-21). Author: 坦途国际教育
5
votes
2answers
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 ...
5
votes
1answer
554 views

Rolling a dice - Expectation Question [closed]

I heard / read / acquired this puzzle from somewhere: Roll a die, win $2\times$ the value of the face if it is an even number, or win $1\times$ the value of the face if it is an odd number. How ...
0
votes
3answers
513 views

Simple Math Problem #3

Previous Puzzles(Not linked to this one): Simple Math Problem #1 and Simple Math Problem #2 Prove the equation: $-6439832+ = 9$ $-$ and $+$ are there just to tell that you can use only these two ...