Questions tagged [factorial]
This tag is for challenges involving the factorial of a number, the product of the numbers from 1 to n
30
questions
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Convert real numbers between factoradic and positive integer bases
This prompt asked you to convert back and forth to factoradic, but is very limited in scope (only decimal integers from 0 to 10!-1). Your task in this challenge is to reach just a bit further and ...
- 1,053
15
votes
14
answers
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views
How many trailing zeros in the hyperfactorial?
We have a challenge to calculate the hyperfactorial and one to count the trailing zeros of the factorial, so it seems logical to put them together and count the trailing zeros in the hyperfactorial.
...
- 6,348
8
votes
7
answers
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Factorials of primes decomposition
You have to decompose a positive integer/fraction as a product of powers of factorials of prime numbers.
For example
...
- 5,099
18
votes
3
answers
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views
Find a factorial with n trailing zeros, quickly
Problem
A fact you may have noticed about factorials is that as \$n\$ gets larger \$n!\$ will have an increasing number of \$0\$s at the end of it's base \$10\$ representation. In fact this is true ...
- 99k
4
votes
1
answer
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views
Calculate the (n x "super")factorial [duplicate]
Introduction
Factorials are one of the most frequently used examples to show how a programming language works.
A factorial, denoted \$n!\$, is \$1⋅2⋅3⋅…⋅(n-2)⋅(n-1)⋅n\$.
There is also the ...
- 563
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votes
22
answers
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Implement the Torian
The Torian, \$x!x\$, of a non-negative integer \$x\$ can be recursively defined as
$$
x!0 = x \\
x!n = \prod^x_{i=1} i!(n-1) = 1!(n-1) \times 2!(n-1) \times \cdots \times x!(n-1)
$$
The Torian is then ...
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20
votes
9
answers
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Zeroes at end of \$n!\$ in base \$m\$
Related: Zeroes at the end of a factorial
Today, we are going to calculate how many zeroes are there at the end of \$n!\$ (the factorial of \$n\$) in base \$m\$.
Or in other words: For given integers \...
- 35k
57
votes
154
answers
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The vanilla factorial challenge
Task
Given a non-negative integer \$n\$, evaluate the factorial \$n!\$.
The factorial is defined as follows:
$$
n!=\begin{cases}1 & n=0\\n\times(n-1)!&n>0\end{cases}
$$
Rules
All default I/...
- 77.5k
20
votes
9
answers
665
views
Prime Modified Z-Factorials
Let me explain one by one the above terms...
We will call \$\text{Z-Factorial}(n)\$ of a positive integer \$n\$, \$n!\$ (i.e. \$n\$ factorial) without any trailing zeros.
So, \$\text{Z-Factorial}(30)\$...
- 24.9k
22
votes
39
answers
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Reverse factorial function
Given a number n, find x such that x! = n, where both x and n are positive integers. Assume the input n will always be the factorial of a positive integer, so something like n=23 will not be given as ...
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38
votes
19
answers
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Bad factorial joke
Sometimes I make bad jokes... And a bad joke I like to make involves interpreting exclamation marks in sentences as the factorial sign.
Task
Your task is to write a program that receives a sentence ...
- 14.1k
39
votes
41
answers
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Repeated! Factorials!
Not to be confused with Find the factorial!
Introduction
The factorial of an integer n can be calculated by
$$n!=n\times(n-1)\times(n-2)\times(...)\times2\times1$$...
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32
votes
21
answers
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A Note on N!
J. E. Maxfield proved following theorem (see DOI: 10.2307/2688966):
If \$A\$ is any positive integer having \$m\$ digits, there exists a positive integer \$N\$ such that the first \$m\$ digits of \$N!...
- 43.9k
1
vote
3
answers
893
views
Finding Factorials with Gamma [duplicate]
Introduction
We know that the factorial notation is valid for all natural numbers. However, Euler had extended it for all positive real numbers, as well as for complex numbers by defining a function, ...
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16
votes
5
answers
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Factoring factorials
Today in my statistics class, I found that some factorials can be simplified when multiplied together! For example: 5! * 3! = 5! *3*2 = 5! *6 = 6!
Your job:
Given ...
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