Questions tagged [calculation-puzzle]

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

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Multiplication Homework

$7*7~$ is $~25$ $6*6~$ is $~18$ $9*9~$ is $~41$ When is this true? Hint
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Replace all letters with a digit and solve the equations

There are ten expressions written in the scheme below from left to right and top to bottom. Replace all of the ten distinct letters in the scheme with a single digit between 0 and 9 and make the ...
469 views

Boat traveling on a river [closed]

There's a boat traveling on a river. When it's going with the river flow, it takes 10 minutes to cover 1km, but when going against the flow, it takes it 15 minutes. How long does it take to cover 1km ...
258 views

When did the tournament start?

[Inspired by the movie Bloodsport] The Kumite is an illegal underground fighting tournament organized in the typical single elimination bracket style. Think March Madness. All fights are fought one ...
173 views

A man on a hill [closed]

A man walks up a hill at 2mph, and back down the same way at 4mph. Upon returning to where he started, what is his average speed?
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SPEND LESS MONEY alphametic

The well-known verbal arithmetic problem S E N D + M O R E ----------- M O N E Y explains (or at least it did the first time I knew about it) the story ...
86 views

Average rain for 7 days [closed]

Assuming that Average rain rained for 7 days is 7 cm. First 6 days's average rain rained is 6 cm, then how much is rain rained on the 7th day of the week?
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"Hey! If I were to add 6 to 13 I would get 7!", said Patrick slowly as he blew a stream of suspiciously maroon smoke out through his left nostril while calmly stabbing a funny-looking cigarette into ...
815 views

A different extension of the sum and product puzzle

How far down the rabbit hole of not knowing can we go? While working on the generalization of I don't know the two numbers... but now I do, I thought of these two extensions. Both have the same ...
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Generalization of Sum and Product puzzle

I heard from a clever person that for the problem mentioned before: I don't know the two numbers... but now I do a solution exists even if we change 100 to infinity. So the formulation would be ...
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 ...
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“Magic: the Gathering” Challenge #3: Legends Rule

Previous Challenge Next Challenge BACKGROUND: Assume that this is a normal 20-life game of magic with no banned list (excepting cards from the 'Un' sets). If multiple solutions are tied for the ...
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“Magic: the Gathering” Challenge #2: Two Peas in a Pod

Previous Challenge Next Challenge BACKGROUND: Here's a puzzle for Magic: the Gathering players out there. I feel that this puzzle is in the scope of the site, and is no different than other puzzles, ...
653 views

“Magic: the Gathering” Challenge #1: A Fiendish Puzzle

Next Challenge BACKGROUND: Here's a puzzle for Magic: the Gathering players out there. I feel that this puzzle is in the scope of the site, and is no different than other puzzles, e.g. chess, which ...
254 views

Colored stones on a chess board puzzle [closed]

We have a chess board of size n x n and there is exactly one stone on every square. We have green, blue and red stones. We must not have a row or a column full of stones of the same colour. We can ...
196 views

What will be the missing number? [closed]

What number comes next? 11,13,17,19,23,25,?
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Walking and cycling [closed]

Claire walks to work at 6km/hr and Charles cycles along the same route. Normally Charles overtakes Claire outside the public library. One day Claire leaves 20 minutes late and Charles overtakes her ...
687 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 ...