Questions tagged [calculation-puzzle]
A puzzle that involves numerical calculations, such as multiplication and addition. Use with the [mathematics] tag.
1,241 questions
9
votes
1
answer
569
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When is the next "Factorion" date?
A "Factorion" date is a date such that when written to either one of M!+M!+D!+D!+Y!+Y!+Y!+Y! (MM/DD/YYYY), D!+D!+M!+M!+Y!+Y!+Y!+Y! (DD/MM/YYYY) , or Y!+Y!+Y!+Y!+M!+M!+D!+D! (YYYY/MM/DD) is ...
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8
votes
2
answers
475
views
Find a number whose divisors' factorials add up to a given number
This question did never came out in any contest.
If $\sum_{d\mid n} d!=$ ...
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-4
votes
2
answers
237
views
Make numbers 1-40 using only 2, 0, 2, 6
Try to make all numbers 1-40 using the digits 2, 0, 2, 6.
Rules:
Use all four digits exactly once.
Allowed operations: +,−,×,÷,! (factorial), $x^y$ (exponentiation), √ (square root).
Parentheses and ...
7
votes
2
answers
1k
views
Why does that person have a phobia on these dates?
Note: I created this puzzle.
A person has a phobia on certain dates - January 15 and February 3. While some dates like April 15 and July 24 also appear unlucky, that person is more afraid of those ...
- 1,403
5
votes
0
answers
306
views
An old book with an ancient numeral puzzle: How many coconuts?
I came across the following puzzle in "Puzzles, Patterns, and Pastimes from the World of Mathematics" by Charles F. Linn (https://archive.org/details/puzzlespatternsp00linn/ page 50):
For ...
- 151
12
votes
1
answer
619
views
Pattern of the Chessy Sequence
Find the pattern of the chessy sequence.
Kn1 = 43x73x101x137
Kn2 = 25x41x26161
Kn3 = 43232323
Kn4 = 2x16170607
Kn5 = 32x4801369
Kn6 = 23x32x7x59x1087
Kn7 = 32x4801369
Kn8 = 2x16170607
(All of the ...
- 5,168
7
votes
2
answers
1k
views
How much am I? - Four-digit number riddle
I came from any distinct four-digit number.
While I was it, I reordered myself, marking my maximum and minimum.
I saw a difference between them, then made that difference myself.
I repeated this until ...
- 5,168
7
votes
2
answers
771
views
Find the Hidden Rule!
Handmade Puzzle.
Solve the puzzle, and find the hidden rule. (This is not evil.)
[Notations / Rules]
0. Latin Square - Each rows and columns should have distinct digits from 1~9.
1a. - Maximum cell: ...
- 5,168
8
votes
2
answers
835
views
Determine if there exists a future date such that the sum of digits of MM/DD/YYYY is equal to ⌊√yyyy⌋
Note: I created this puzzle.
Determine if there exists a future date such that the sum of digits of MM/DD/YYYY is equal to $\lfloor\sqrt{yyyy}\rfloor$, where MM is the month, DD is the day, and YYYY ...
- 1,403
33
votes
2
answers
2k
views
2.25³ᐧ³⁷⁵ vs 3.375²ᐧ²⁵
Without using a calculator or a computer can you determine which of these two numbers is bigger: 2.253.375 or 3.3752.25?
- 39.7k
5
votes
2
answers
659
views
Does this even have unique solution? - Logic Steps Blocked -
Solve this puzzle.(Handmade)
Rules:
Every rows and columns should have unique digits(1~9) once.
Regions(): Yellow-colored cells should not have same digits.
Max(): Bigger than adjacent cells.
Min(): ...
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3
votes
3
answers
217
views
With given numbers, make the number 87 [closed]
Try to make the number 87 using 5,5,1,0
Rules:
Use all four digits exactly once.
All mathematical operations are allowed.
Concatenations are not allowed.
- 31
6
votes
1
answer
512
views
This is not about the last century...
1926 $\longrightarrow$ 19
1927 $\longrightarrow$ 16
1928 $\longrightarrow$ 20
1929 $\longrightarrow$ 19
1930 $\longrightarrow$ 19
1931 $\longrightarrow$ 15
1932 $\longrightarrow$ 18
1933 $\...
- 7,958
16
votes
2
answers
792
views
Moving water by repeated equilibration
There are 100 full water tanks and 100 empty ones. You are given a hose that can connect any two of them in order to equilibrate the water level between them. All the tanks are cubical in shape, of ...
- 263
15
votes
3
answers
1k
views
How many measures to know the area?
How many measures are required to figure out the area of the annulus below?
(The center of the two circles are equal.)
Attribution to my math lecturer. :)
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