Questions tagged [calculation-puzzle]

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

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votes
1answer
2k views

Finish The Pattern #1 [closed]

Given a pattern: 12, 22, 35, 68, 15, 28, 31, $n$ Find the next item at $n$. Pattern/sequence explanation required
7
votes
2answers
3k views

Find the age of the ship and of the boiler

Some years back I was travelling by a cargo ship from New Zealand to Tahiti. I was curious to look around the ship one day and in the boiler room I asked a man how old the ship was. He smiled and ...
5
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2answers
1k views

What is the maximum number of cities that can be destroyed?

As a commander of an army battalion, you have to plan the attack on some enemy cities which are connected by road-network. Before starting the attack, you have information about all the cities and ...
6
votes
4answers
2k views

To be a bookworm

I have a complete set of encyclopaedias on my bookshelf, beautifully bound and neatly arranged with volume 1 on the left and volume 32 on the right. They were a talking point when I bought them 30-odd ...
1
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6answers
562 views

How many Pigeons are there?

There are pigeons sitting in a queue. The first one said, "There are 4 pigeons behind me." The last one said, "There are 4 pigeons in front of me." The middle one (or, one of middle ones) said, "There ...
-2
votes
1answer
2k views

Calculating row number and column number [closed]

What I am trying to do is calculate the row and column of which an id is in. For example I have the grid 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 As you ...
0
votes
2answers
266 views

What is my room?

You are heading to your hotel room but forget your room number. Try to check the key card but the digits are blurred You call to hotel desk info and a nerdy bell boy tell you: Your room have 4 ...
13
votes
1answer
1k views

A Quote from what Movie?

Heads up: It's possible to solve this puzzle without writing computer code, but it is intended to be solved with computer help. This is a 2-stage puzzle. Stage 1: Calculation Puzzle Rules: 1. You ...
8
votes
3answers
2k views

Vegas Street Magician Math Trick

I went walking with a friend of mine in Las Vegas last week. We turned a corner and saw a street magician doing some tricks for a crowd of 12-15 people. In most of his tricks, the magician would make ...
2
votes
1answer
252 views

How Much Bread For Her Budget? [closed]

A woman is looking through a store and sees a sign for 2 dollar bread saying "For every 10 loaves you buy, you get each for only 1.9 dollars!" A pretty strange deal, but she decides to take it. If ...
7
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2answers
470 views

Bitwise multiplication

Mr. EG has come up with a great coding scheme for (non-negative) integers in binary. To show off his creation, he demonstrates the following multiplications: ...
-4
votes
1answer
760 views

Time teaser - clock losing time [closed]

I recall a question that went like this: If a clock is at noon on Sunday, and the clock loses 9 minutes per hour, what time will the clock next show the correct time? How do you work that one out?? ...
10
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4answers
1k views

A number and its square

Find a four-digit number which is equal to the four least significant (rightmost) digits of its own square.
-3
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1answer
2k views

How many would die after E slightly pushes the structure in front of him? [closed]

As you can see in the picture, there are 5 people A, B, C, D, E. E is going to slightly push the circular structure so that the initial velocity of the structure on the inclined plane would be zero. ...
18
votes
26answers
11k views

Building a 2 mile runway on a 1x1 mile island [closed]

You have a 1-mile long x 1-mile wide island. When taking off from a flat runway, a plane requires a runway of minimum length 2 ...
36
votes
5answers
5k views

My grandfather's socks

My grandfather has a big drawer where he keeps his socks. The drawer contains more than 900 but less than 1000 individual socks. Each of his socks is black or blue, and there are more blue socks than ...
11
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3answers
2k views

A self-referring number

Find a ten-digit number with the number of zeros in it as the most significant (leftmost) digit, the number of ones as the second most significant digit etc.
-3
votes
1answer
276 views

Arithmetic/Knowledge Step-By-Step Number Puzzle! (What Is The Final Answer?) [closed]

Start with the number of U.S. ounces in a U.S. gallon. Subtract the atomic number for Samarium. Add the amount of days in February on a leap year. Multiply this by 6 factorial. Divide this by pi ...
1
vote
0answers
225 views

Shooting an invisible rabbit [duplicate]

An invisible rabbit sits on one of the posts of an infinite fence. A local farmer cannot stand this fact and wants to shoot the rabbit down*. Every time the farmer shoots her gun, the rabbit jumps to ...
4
votes
4answers
721 views

Start with an unlucky Friday

Start with an unlucky Friday number. Multiply by the gables on Hawthorne's house. Add the number that a stitch in time saves. Add the number of blind mice. Subtract the number of William Pene du Bois' ...
30
votes
1answer
2k views

Computation without a computer

In the number $(1+\sqrt{3})^{2015}$, what is the 224th digit after the decimal point? You may NOT use a calculator, computer, or any electronic aid to answer this question. Only pen(cil), paper, and ...
7
votes
3answers
2k views

3x3 “Magic Square” of Prime Numbers — Part II

Glad to know the previous puzzle, which was the first puzzle I posted in Puzzling, was warmly welcomed (Thank you!), and an optimal solution was found. Inspired by the comments there, here is the ...
9
votes
2answers
2k views

What is the next term in the sequence?

The first term is f(0), the last term is f(2000): 0,0,0,0,1,0,1,0,2,1,1,0,2,0,1,1,3,0,2,0,2,1,1,0,3,1,1,2,2,0,2,0,4,1,1,1,3,0,1,1,5,0,2,0,2,2,1,0,4,1,2,1,2,0,3,1,5,1,1,0,3,0,1,2,6,1,2,0,2,1,2,0,4,0,1,...
2
votes
1answer
390 views

What will be the price of the dog? [closed]

Two men had a certain number of camels, and sold those camels. The price of each camel was equal to the total number of camels they owned initially. They then bought a certain number of goats for that ...
-5
votes
3answers
297 views

Scrap puzzle to count how many

There are 250 scraps. For each 11 removed, one extra can be obtained. How much maximum is possible, if one cut by one unit? I have read this somewhere, and one guy gave the answer as 25, but I can't ...
-2
votes
1answer
269 views

There's an ARG I've been working on, and I'm stuck on this puzzle part II

Hees the first one incase you havent seen it. There's an ARG I've been working on, and I'm stuck on this puzzle So from that we got our password for this "problem" however we havent ...
7
votes
3answers
895 views

The Wizard's Gambit

An evil wizard has captured and thrown you into a dungeon. This is not a normal dungeon though. It's magical. Each room has an associated "level" and 9 doors. The first door can be used to go to ...
-3
votes
1answer
1k views

Working schedule (with explanation) [closed]

Alice, Bob, Chris, Dave, Eric, Fred and Laura used to work in a restaurant 6 days a week, from Tuesday to Sunday (Monday is a day off). Every one works at least for one day, and at least two people ...
-2
votes
1answer
257 views

Calculate RPM ratio A to D? [closed]

According to the picture: cogwheels A and D have 60 jags each, cogwheel B has 40 jags, and cogwheel C has 20 jags. If cogwheel B turns at 20 RPM, calculate the ratio of A's speed in RPM to D's.
17
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3answers
3k views

In a certain language if the word STABILIZE is coded as JHXDJQSYA, then how is the word RESPONSES coded in that language?

In a certain language if the word STABILIZE is coded as JHXDJQSYA, then how is the word RESPONSES coded in that language? LRCRPOQDP PDQOPLRCR LRCRPPDQO LQCRPPDQO LRCRPPDOQ I tried it ...
14
votes
2answers
839 views

Dragon lizards in Hogwarts

Albus Dumbledore keeps 274 dragon lizards in his terrarium in Hogwarts. One day he removes two thirds of the male lizards from the terrarium; it is easy for him to tell the males apart from the ...
25
votes
3answers
3k views

What, the answer isn't the No of the Yes is?

Doorknob knows exactly how to solve this, so I ask him to not answer this question. Well, here's the puzzle: No, an answer is the cube without A, No? The Yes is No. The squared answer, Yes, is to an ...
9
votes
2answers
2k views

Integer grid problem

I found this programming related problem too difficult for me. The problem asks to find 16 integers and form a 4x4 grid $$\left(\begin{array}{cccc} n_1 & n_2 & n_3 & n_4 \\ n_5 & n_6 &...
-2
votes
2answers
206 views

Shifting the stack as it is

There are $3$ saucers. And there are $5$ disks, say A,B,C,D,E, having respective areas $1,2,3,4,5$. That is, E is the largest disk and A is the smallest one. They are placed in the order E,D,C,B,A in ...
-2
votes
11answers
13k views

What's your price for the eggs? [closed]

I came across this problem some years ago in a book (which I won't mention, and request others to not mention if they know). The solution is quite elegant and difficult to arrive at by mere trial and ...
6
votes
1answer
1k views

Puzzle of Random Numbers

My friend sent me his puzzle: it's S2LQEQnXk4DP+WsyP1aURD+lz4JSteeOPz3tO7Yiu1dv5fFCr31uegHUpVGqyXk7WjX95TDALus8Gj6nnoGHwj0MLE2AfpB2KTQEIxVvGMyun2XLb+PTcqzVAoFQLr48 ...
1
vote
3answers
460 views

Balance the Equation

Peter found an old piece of paper that an equation was written on it. Some of digits or operations are unreadable. Help Peter to complete the balanced equation. The equation is: $87+?3?12-4?2=?36-15??...
13
votes
1answer
830 views

A building with an odd elevator

In a building, there is an odd elevator, which has only two buttons: UP, which makes it go up 9 floors, and DOWN, which makes it go down 7 floors. (The ground floor is floor 0.) It is possible to ...
2
votes
5answers
3k views

The story of green apples and red herrings

Let's say we are in a magic land with lots of fantastical animals and plants and whatever... Imagine you have way too much time, really like apples and love collecting and growing them. In fact, ...
10
votes
6answers
7k views

Aeroplane roundtrip in the wind

If an aeroplane makes a round trip and a wind is blowing, is the trip time shorter, longer or the same as without wind? Why? Round trip mean aeroplane go from point A to point B and then return to ...
3
votes
4answers
24k views

Find length, width and height of a cuboid [closed]

Consider a cuboid (that is, a rectangular box / rectangular parallelepiped) with the following properties: the area of its top face is $240$ cm$^2$ the area of its front face is $300$ cm$^2$ the ...
5
votes
2answers
516 views

Quick and dirty: painting a fence

There are four fences, which are geometrical identical (same heigth and same length). The following four people need the specified time to paint it: Bob needs 2 hours. Simon needs 3 hours. Tommy ...
30
votes
7answers
8k views

Aside from brute force, how can I solve this puzzle?

Once upon a time, and old lady went to sell her vast quantity of eggs at the local market. When asked how many she had, she replied: Son, I can't count past 100 but I know that: If you ...
7
votes
1answer
1k views

Probability of Seeing a Car in 10 Minutes & 30 Minutes [closed]

On a deserted road, the probability of observing a car during a thirty-minute period is 95%. What is the chance of observing a car in a ten-minute period? Hint: To clarify the question we are saying ...
3
votes
2answers
2k views

whats the Missing Number?

In this grid of numbers, what is the missing number (in place of the question mark)? $$\begin{array}{|c|c|}\hline2&7\\\hline8&9\\\hline\end{array} \begin{array}{|c|c|}\hline0&3\\\hline5&...
12
votes
5answers
3k views

Sequence Brain Teaser: Fill the gaps to create arithmetic sequences

Fill in each blank unshaded cell in the diagram below with a positive integer less than 100, such that every consecutive group of unshaded cells within a row or column is an arithmetic sequence. This ...
7
votes
4answers
634 views

Paint the rectangle with least movement

There is a painting brush tool that can paint a circle area of $1$ unit radius. What is the shortest paint track for painting at least a $100*100$ units rectangle area on wall? How much did the brush ...
14
votes
4answers
965 views

The lights in the hotel

A hotel has $n$ rooms, numbered 1, 2, 3, etc. until $n$. At the hotel reception there are $n$ buttons, one for each room, also numbered 1, 2, 3, ..., $n$. Button 1 switches the light from on to off or ...
2
votes
1answer
757 views

Can the car or the bike travel further?

There is a car and a motor-bike. The car and the bike both have an spare tire. Now, the car has a total of 5 tyres (one spare tire included) and the bike has a total of 3 tires (one spare tire ...
7
votes
2answers
1k views

Need help solving this code puzzle. Possible binary?

Me and a friend are trying to solve a series of puzzles, and this is the last one I need to solve and I'm stumped. It's a Christmas themed puzzle titled 'bLitZEN'. The only hints given are that the ...