Questions tagged [calculation-puzzle]
A puzzle that involves numerical calculations, such as multiplication and addition. Use with the [mathematics] tag.
1,017
questions
5
votes
0answers
82 views
Turn the dials until each of the 12 columns add up to 42
I received the wooden puzzle below for Christmas. After playing with it for a while I decided I needed to actually write something down if I was going to solve it. Eventually I just wrote an algorithm ...
-4
votes
1answer
97 views
Quantity expressed as the difference of two squares
What is the trick you need to use to be able to express the quantity
$(4x^4+8x^3+7x^2+3x+\frac{1}{2})$
as the difference of two squares?
addendum: The answer contains only rational numbers greater ...
-5
votes
3answers
128 views
What is the Result of this icon Equation? [closed]
from:https://www.rondogo.sk/hra
I have problem with heart :)
A) 19
B) 20
C) 21
D) 22
-2
votes
2answers
111 views
What is the right number to replace and why?
Can anyone help me solve these puzzles?
Puzzle from: www.treningmozga.com
4
votes
3answers
879 views
Finding a Kakuro trick
The following screenshot is taken from the Android app Kakuro++ (level 9 riddle 12)
And I verified the current status within the app. I managed to solve the puzzle by guessing a 50/50-number and ...
2
votes
1answer
255 views
What number is missing in the pentagon? [closed]
What number is missing in the pentagon?
Puzzle from: https://www.rondogo.sk/hra/
1
vote
1answer
93 views
Equal row-products and column-products in a given array [closed]
I don't know if this is the right place to ask this question, but I'm stuck on this and can't figure out how to even proceed. Any hints anyone?
Is it possible in a 5 × 5 array of integers for all row ...
1
vote
1answer
126 views
Math riddle puzzle
I stumbled upon this math puzzle over one android app.
You need to find the unknown number in the puzzle.
92 = 725
61 = 215
74 = 327
52 = ?
According to the author ...
2
votes
3answers
237 views
Reversible number problem
These are the reversible numbers
In this example we have an operation that on one side gives the result 6 and turning it gives it 12.
Is it possible using reversible numbers and mathematical ...
2
votes
2answers
348 views
Minimum number of questions?
This is an interesting puzzle which I've been racking my brain to solve for some time. I've found different variations of this puzzle but it does not seem like this one has been asked before. Here it ...
3
votes
0answers
240 views
What's the missing number in this 3x4 matrix? [closed]
$$
\begin{matrix}
3 & 3 & 5 & 6 \\
2 & 3 & 6 & 1 \\
7 & 6 & 3 & x \\
\end{matrix}
$$
This math puzzle is supposed to be solved by middle school ...
3
votes
0answers
250 views
Find a missing number in this 28x21 grid
355|066|677|855|677|081|044|855|355|062|216|677|216|855|224|044|034|046|051|677|355|264|044|046|044|351|886|043
043|044|886|357|886|352|225|357|043|222|993|001|233|968|046|225|062|041|351|886|043|227|...
6
votes
2answers
535 views
Math puzzle: I know the answer, what is the equation? Use all digits 1-9
A few years ago, my child brought a puzzle home from their 6th-grade math teacher. The solution was to use all the numbers $1−9$ only once and make the equation true. Using a spreadsheet, I was able ...
2
votes
1answer
168 views
Fill each blank with a digit 1-9 without any repetition [closed]
Fill the following place holders with digits in the range from 1 to 9. Each digit only appears once and make the equation sum up to 100.
_ /_ * _ + _ * _ * _ / _ + _ * _ = 100
Also, what is the ...
-5
votes
1answer
104 views
-4
votes
1answer
106 views
Clock puzzle - 17:45 + 22:05 = 1510 [closed]
I have designed this clock puzzle for you to solve!
$17:45 + 22:05 = 1510$
$20:55 - 17:30 = 35$
$06:40 * 19:20 = ?$
5
votes
1answer
137 views
The digits of the cube of a 3-digit number X
The digits of the cube of a certain 3-digit number X are, from left to right, the square of a 2-digit number, followed by the square of another 2-digit number, followed by one digit. (Everything is ...
0
votes
2answers
92 views
Which number replaces the question mark?
I'm trying to solve puzzles to exercise my brain. I'm stuck on this test, I printed it from Mensa IQ Test, an app on Android store. Can someone help me?
Below is the test:
-8
votes
1answer
129 views
Puzzling rectangles [closed]
Can you find two unequal rectangles whose areas add to $5\sqrt5$?
No computer solutions please.
15
votes
3answers
987 views
A Perfect Diamond of Numbers
A diamond of numbers is an arrangement of circles in the shape of a trapezoid (see figure) in which the number in any circle above its central (longest) row is the sum of the two numbers in the ...
asked Sep 16 '21 at 14:41
Bernardo Recamán Santos
13.9k2 gold badges23 silver badges129 bronze badges
31
votes
2answers
3k views
Sum of the first 86 square roots
Without using a calculator or a computer, can you compute the sum of square roots of the first 86 natural numbers, rounded to the nearest integer? In other words, we are looking for $\sqrt{1} + \sqrt{...
3
votes
1answer
252 views
Six single-digit numbers surrounding a three digit number - what's the rule?
Source: SOF World IMO Class 9
Find the missing number, if the same rule is followed in all the three figures.
2 1 4 2 3 3 4 6 7
\ | / \ | / \ | /
693 374 ?
/ | \ / | \ /...
9
votes
2answers
358 views
Climbing scoring puzzle inspired by today's olympic event
Necessary information. The sport climbing consists of three disciplines: speed climbing, bouldering, and lead climbing. In combined events, the disciplines come in this order, and the combined score ...
-2
votes
2answers
154 views
How to solve this problem on overlapping?
In cases of problems involving order and ranking where there are two indices (namely left and right) there is a particular chance of overlapping. Let us take an example to justify this:
Ranjan is ...
0
votes
1answer
175 views
Puzzle storm to infinity
I have been playing Puzzle Storm on Lichess lately. Essentially it involves solving chess puzzles within a given time limit. Additionally, the player gets a time bonus for a certain number of moves. ...
5
votes
1answer
153 views
Sum and product of 9 digits
Adding single digits 1 to 9, the result is 45 and their product is 362880.
Are there any other 9 single digits with sum 45 and product 362880?
3
votes
0answers
113 views
Expected waiting time [closed]
You arrive at a station at time t=0. Train A can come anytime between [0,5] and train B can come anytime between [0,7] and train C can come anytime between [0,9]. You will board the first train you ...
-1
votes
1answer
240 views
Grandfather and Grandson
My Puzzle is as follows-
Once, I said to my friend that, "In 1932 I was as old as the last two digits of my birth year. When I mentioned this interesting coincidence to my grandfather, he ...
-1
votes
1answer
252 views
What's a general method to solve this calculation puzzle?
I need help to work out how to solve this puzzle. The puzzle is very self-explanatory...
2
votes
1answer
167 views
0
votes
2answers
158 views
Find out the odd one in the diagram
I'm solving puzzle from the book super excellent and intellegent test. Im stuck on these. Someone said answer should be 983. But how? Can anyone tell me the right answer. thanks.
0
votes
1answer
321 views
what number should replace the question mark in hexagon diagram? [closed]
I'm trying to solve this problem from a book, but can't understand how it works. Why is 12 in the center? What should be the missing number?
7
votes
2answers
437 views
Is $\sqrt1*\sqrt2*\dots*\sqrt n$ ever an integer?
Is $\sqrt1*\sqrt2*\dots*\sqrt n$ ever an integer?
Note: Deusovi has already given a nice and simple answer. I still wish to welcome more answers as I want to see if there are other ways to approach ...
8
votes
2answers
1k views
Spending 1374.00 US dollars in three days
Jenny received 1374.00 US dollars which she has to spend all or a portion of within 3 days, with the following conditions.
The percentage (of her current dollars) which she is allowed to spend each ...
11
votes
2answers
503 views
Adding rows of blanks
I was looking at this short video, and it made me think of a puzzle.
Let's say you have this set of equations:
...
-5
votes
1answer
124 views
Equation 60 divide by 2 [closed]
This puzzle is from YouTube
60 / 2(10+5) = ?
The answer mentioned is 450. The same answer is shown by Google. But, I believe the answer is 2.
Is the answer 2 or 450?
2
votes
5answers
838 views
Can you fill the cells by integers? [duplicate]
Can you fill the cells with integers so that all the equalities must be true?
1
vote
1answer
615 views
Make 1-100 using 2 0 2 2
You may use the following:
Addition [e.g. 2+2]
Subtraction [e.g. 2-2]
Multiplication [e.g. 2x2]
Division [e.g. 2/2]
Decimal point [e.g. 2+.2]
Exponents [e.g. 22] {tetration is NOT allowed}
Square ...
2
votes
5answers
401 views
Largest pair of consecutive numbers, not greater than a million, that can be expressed with four fours [closed]
What is the largest pair of consecutive numbers, not greater than a million, each of which can be expressed using precisely four fours and an assortment of standard operators (including concatenation, ...
asked May 12 '21 at 16:58
Bernardo Recamán Santos
13.9k2 gold badges23 silver badges129 bronze badges
-2
votes
1answer
140 views
How old are Jim and John? [closed]
(Disclaimer: I remember a puzzle like this I did a long time ago, but this isn't a direct copy of the puzzle, only it's formatting. If this is appears to be a copy of another riddle, I will simply say ...
11
votes
1answer
1k views
My grandfather's coins
When my grandfather died, he left his fine collection of coins, not more than 2500 of them, to his children, a different number to each of them, and in decreasing amounts according to their ages.
To ...
asked Apr 12 '21 at 1:43
Bernardo Recamán Santos
13.9k2 gold badges23 silver badges129 bronze badges
13
votes
3answers
2k views
What is the age of the old man?
In autumn of the year 2003 an old man was asked about his age.
He answered: "I was born on a Sunday morning in summer and I celebrated my seventh birthday
on a Sunday morning too!"
How old ...
0
votes
1answer
124 views
Work to time ratio! [closed]
Once Valera left the house, walked to the villa, painted 11 fence boards there, and returned home
2 hours after leaving. Another day, Valera went to the villa with Olga, together they painted 8
fence ...
8
votes
5answers
1k views
Split 1 through 6 into a product of 24 and sum of 12
How many ways are there to split the numbers 1, 2, 3, 4, 5, and 6 into two groups, such that the product of the numbers in one group is 24 and the sum of the numbers in the other group is 12? An ...
10
votes
3answers
928 views
Calculation Sudoku
Here is a new quiz from my daily quiz calendar. I'm trying to find a way to solve it.
The numbers 1-6 should be filled in. And like a sudoku, each row and each column should contain each number ...
-4
votes
1answer
179 views
Not a music rebus
What is the 6-letter word that associates with this rebus?
Helpness Meter 1:
Helpness Meter 2:
Helpness Meter 3:
2
votes
1answer
89 views
Find the pattern of the following series: 7 × 3 = 5? [closed]
I recently came across a certain question which I was not able to solve.
It was as follows:
7 × 3 = 5
9 × 5 = 41
15 × 11 = ??
Can you tell me the logic behind this?
4
votes
1answer
288 views
Multiplying English numbers is strange too
It seems that the English-speaking people multiply the numbers in the very same way that the Portuguese add them: while the latter say that 2+2=8, the former claim that 2×2 is 8:
...
3
votes
2answers
217 views
Pirates dividing booty around a circular table
A group of pirates have plundered one of his majesty's cargo ships and they all carried as much gold coins as each one could find. When they get back to their ship, they sit at a round table and pass ...
-4
votes
1answer
121 views
A Clear, Simple, Geometry Problem [closed]
Draw a shape consisting of all the points equidistant from a specific point. Furthermore, draw a segment passing through a side of the shape exactly twice, and draw another segment so that it also ...
