# Questions tagged [factorial]

This tag is for challenges involving the factorial of a number, the product of the numbers from 1 to n

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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 ...
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### 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. ...
654 views

### Factorials of primes decomposition

You have to decompose a positive integer/fraction as a product of powers of factorials of prime numbers. For example ...
634 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 ...
254 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 ...
3k views

### 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 ...
621 views

### 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 \...
8k views

### 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/...
660 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, $\text{Z-Factorial}(30)$...
3k views

### 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 ...
7k views

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 ...
Not to be confused with Find the factorial! Introduction The factorial of an integer n can be calculated by $$n!=n\times(n-1)\times(n-2)\times(...)\times2\times1$$...