# Questions tagged [calculation-puzzle]

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

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658 views

### Professor Halfbrain and the next square

Yesterday afternoon I met professor Halfbrain at a coffee place. The professor looked very tired. He told me that he hadn't slept for many days, spending his time with writing lots of zeros and with ...
293 views

### Time Traveller Maths

On a Wednesday afternoon, Marty McFly starts his DeLorean at 14:00 hours and travels 30 years in the past. After spending 3 days 30 minutes, travels 60 years to the future where he stays for another ...
645 views

### Clock values using only the digit 3

What is the minimal number of 3s required to create a clock where each of the hours is replaced by a mathemetical expression using only the digit 3 and standard mathematical operators? A friend ...
461 views

### Lionel Messi's soccer puzzle

Lionel Messi sentimentally remembers a small soccer tournament in which he participated many years ago. There were four teams in the tournamnent: Atleticolino, Barcelino, Chicorrotico and Diminuto. ...
178 views

### A Chuck-a-luck variant

You're thinking of trying a variant of Chuck-a-luck. In this variant, you choose one number in the range $1$ to $6$ and five dice are rolled. These are the payouts: ...
647 views

### First to Five Points

The Problem: There are two players. Each player writes a number, hidden from the other player. It can be any integer 1 or greater. The players reveal their numbers. Whoever chose the lower number ...
3k views

### A new six-sided die

Enrico wants to construct a new six-sided die with the following properties: Each side should show a positive integer Different sides should show different integers If two sides share an edge, then ...
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 ...
666 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 ...
640 views

### Largest number with five 1's and five numeric operations [closed]

You have five 1's at your disposal, together with five arithmetic operations of your choice. However, as you only have five operations, you should choose them wisely. Question: What is the largest ...
606 views

### A puzzle about flies and trains

So I have a website with some job interview type questions on it. Yesterday I pulled a question out the depths of my memory: A train enters a station at 50m/s where it starts to decelerate ...
2k views

### A sloppy calculation

Little Johnny Red forgot to write the multiplication sign between two 3-digit numbers $x$ and $y$ and simply wrote them as one number. When Johnny's teacher graded the homework, it turned out that the ...
969 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 ...
479 views

### May the fours be with you!

In the picture above, all the numbers 1-12 are given, using only three nines. Now, I want to make a similar watch, but using fours instead of nines. Can you make a list of the numbers 1-12 using ...
412 views

### Whose lock is lock-ier?

Two friends, Amy and Ben, each use a three-disk combination lock to secure their bikes. Each disk has $10$ orientations, with integers $0$ to $9$, so there are $10^3$ possible combinations. One day, ...
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 ...
4k views

### For how long did Lisa walk?

Lisa gets picked up from work by her husband at exactly 4 pm every day. One day Lisa finished work half an hour earlier and started walking to meet up with her husband. She met her husband on the way, ...
475 views

### Professor Delvershys calculations

After spending half of the night with important calculations Professor Delvershy arrived late this morning. To his dismay he discovered that one of his students used the unexpected spare time to ...
1k views

### The Magician's Card Game

A magician by the name of Jason carries a deck of cards with him everywhere he goes. He has a game where you can say any phrase and a specific card will correspond with that phrase. The goal of the ...
4k views

### Mr. Hilbert and the Problem of the Erroneous Equation

Having had just checked into the Grand Hotel, Mr. Hilbert slumped into the hotel room armchair with relief. Finally he could have some peace and quiet and solve the quaint riddle his colleague gave ...
552 views

### Another Way to Count Sheep At Night in Bed

I came across this puzzle: A wayfarer asks a shepherd how many sheep he has. He replies that if he numbered them two and two, or three and three, or four and four, or five and five, or six and six, ...
3k views

### All clock hands at equal degrees from each other

My dad once asked me: At what time will the second hand, minute hand, and hour hand on an analog clock all be $120^{\circ}$ from each other? It's a simple question, but I thought it was a fun ...
930 views

### Ernie and the Artificial Emmental

I dropped in on Ernie last week to help him prepare for his annual hosting of the Wine and Cheese Club party. This was a special occasion because the invited guest was the famous oenophile and ...
1k views

### All Words Go to Heaven?

In the fantasy world of this puzzle, Heaven has 7 levels (1 to 7), with 7 being God's level. Hell has 8 levels (-1 to -8), with -8 being Satan's level. Purgatory (0) is somewhere in between. Your ...
300 views

368 views

### Monkey on a Flagpole [closed]

A 3 feet tall, hungry monkey is trying a reach a magical banana placed on top of a flagpole. The flagpole is 25 feet in height and is slippery to grasp. Every Odd numbered Jump, the monkey climbs 3 ...
1k views

### Ernie and the Unexpectedly Exposed PIN

I dropped in on Ernie a few days ago. As I pushed open the door to his workshop I could hear a clanking, hissing noise and then saw Ernie emerging from a great clouds of steam, his face blackened with ...
557 views

### What's Jeremy's Encryption Algorithm?

As a result of their solutions to this puzzle, store owner Jeremy promoted both Cerberus and Quark to top managerial positions. Soon after starting their new roles, they were somewhat surprised when ...
2k views

### An Hourglass Puzzle

This puzzle follows from the well known sand timer puzzles: A Sand Timer Challenge http://www.crazyforcode.com/sand-timer-puzzle/ http://www.cut-the-knot.org/hg_solution.shtml Warmup: You are given a ...
1k views

### What is a Donut Phrase™?

Bwahaha! You're not the only one who can make these puzzles, JLee! (this is an unofficial continuation of JLee's [in]famous Word/Phrase puzzles) The following phrases of varying lengths follow a ...
574 views

### Chile to Singapore

Hey guys, I've been into brainteasers since I was little and recently decided to make a puzzle-related website. I figured that this will be the best place to share some of my problems and see if they ...
204 views

### Depressed Numbers [duplicate]

$12 = 0$ $1234 = 1$ $123456 = 2$ $12345678 = 4$ $369 = 2$ $248 = 3$ $2 = 0$ $3 = 0$ $5 = 0$ $7 = 0$ $11 = 0$ $13 = 0$ What does: $123456789 = ?$ Why? Hopefully isn't too hard, please ask if you ...
129 views

### Minimum number of telephone calls needed to exchange information [duplicate]

There are 16 secret agents who each know a different piece of secret information. They can telephone each other and exchange all the information they know. After the telephone call, they both know ...
2k views

### What is a Surpassing Phrase™?

If a phrase conforms to a certain rule, I call it a Surpassing Phrase™. Use the examples below to find the rule. Some details to save you time: 1. Font doesn't matter. 2. The number of words ...
853 views

### Ernie and the Bubbles of Lucretia

"So, what do you know about milking spiders?", asked Ernie as he passed a fresh cup of coffee to me. Good grief!, I thought and gave an involuntary shudder as I glanced at the milk jug sitting ...
2k views

### Baumic Numbers!

I have a class of numbers; this class of numbers contains a certain number if and only if it is baumic. The following are baumic numbers: 1, 6, 9, 15, 20, 21, 30, 33, 39, 45, 50, 51, 56, 57, 69, 70,...
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 ...
1k views

### Cryptic Woman and a Confused Census-Taker [duplicate]

I recently found a card on which there were two puzzles, both of which have me stumped; I want to spend a little more time on the other puzzle, but here is one that stumps me: no 65 A census-...
633 views

### MC Frontalot 80085

MC Frontalot is a musician, and one of his songs is a word problem that seems to me like it belongs here. If you want to listen to it instead of just reading the lyrics, a quick video search of "MC ...
10k views

### A Water Jug Problem [duplicate]

Suppose you are given two jugs: a 4-gallon one and 3-gallon one, and neither has any markings on it. You have a pump that can be used to fill the jugs with water. What do you do so that exactly 2 ...
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 ...
861 views

### Using the digits 2, 3, 4 make an expression for 30

Write an expression using exactly one 2, exactly one 3, and exactly one 4 to make 30. For each problem, you must use all three of these: Division Factorials (just for regular factorial use, no ...
1k views

### Make 24 and 30 using the digits 3 and 4

First, write an expression using exactly one 3 and exactly one 4 to make 24. Second, write an expression using exactly one 3 and exactly one 4 to make 30. Math You Can Use for each problem: ...
478 views

### What happened to the missing £10? [duplicate]

I have come across a puzzle, which makes no sense. Does anyone know the answer to the below? You and two friends go on holiday. When checking out, the total bill comes to £300. You pay the bill ...
2k views

### A Threes Of Cake

This question is similar to my other question Twos For Thought, which arguably was a better pun but I decided to recreate the question, except with threes! How many threes do you need to get to the ...
575 views

### Twos For Thought

How many twos do you need to get to the number $100$ exactly? Example: $22+22+22+22+2^2+2^2+2^2$ This example method uses 14 twos and is obviously not ideal. Can you find a way that uses the least ...
Find a number $X$ that is 9 times bigger than the total of its digits: for example if $X=abc$, then $X=9*(a+b+c)$. I don't know the number of digits; it could be 3 or 2 or more.