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 ...
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votes
14
answers
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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.
...
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7
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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
...
- 5,107
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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 ...
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votes
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answer
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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 ...
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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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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 \...
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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/...
- 78.4k
20
votes
9
answers
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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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votes
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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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votes
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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!...
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1
vote
3
answers
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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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votes
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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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Additional facts!
In mathematics, the factorial, shortened "fact" of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example, 5! is 1 * 2 * 3 * 4 * 5 = 120
...
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12
votes
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answers
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Do two numbers contain unique factorials?
Break two numbers up into their factorials; if they share any, return a falsey value. Otherwise, return a truthy value. (inspired by this recent question)
In other words, write each input number as ...
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37
votes
30
answers
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Factorials and never ending cycles!
As you may know it, the factorial of a positive integer n is the product of all the positive integers which are equal or smaller to ...
user68509
195
votes
64
answers
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Mathematics is fact. Programming is not
In mathematics an exclamation mark ! often means factorial and it comes after the argument.
In programming an exclamation mark ! ...
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votes
49
answers
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Big numbers: Ultrafactorials
Ultrafactorials
The ultrafactorials are a sequence of numbers which can be generated using the following function:
$$a(n) = n! ^ {n!}$$
The resulting values rise extremely quickly.
Side note: This is ...
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votes
58
answers
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Factorial digit sum
The challenge is to calculate the digit sum of the factorial of a number.
Example
Input: 10
Output: 27
10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800,
and the sum of ...
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votes
44
answers
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Pseudofactorial
There is a rather curious number which shows up sometimes in math problems or riddles. The pseudofactorial(N) is the least (i.e. lowest) common multiple of the numbers 1 through N; in other words, it'...
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Zeroes at the end of a factorial
Write a program or function that finds the number of zeroes at the end of n! in base 10, where n is an input number (in any ...
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votes
10
answers
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Last Nonzero Digits of a Factorial in Base
You should write a program or function which given three positive integers n b k as input outputs or returns the last k digits ...
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1
vote
4
answers
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Memory is Expensive [closed]
You are a robot. You are stranded in a small cage with weird humans wearing weird suits looking at you. Your solar panel is malfunctioning, and your energy is running out. On the wall there is a ...
- 43
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votes
16
answers
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How much can you quickly multiply?
With the recent Python bashing, here's an attempt to show Python's strengths.
Your challenge is to write a program that calculates the factorial of as high a number ...
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31
votes
10
answers
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Calculate the inverse of factorial
Write the shortest code that will take any real number greater than 1 as input and will output its positive inverse factorial. In other words, it answers the question "what number factorial is equal ...
- 1,588
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votes
38
answers
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Factorial in haiku!
Task
Create a program that calculates the factorial of a number using no built-in factorial functions. Easy? The catch is that you must write your entire program (including testing it) in haiku form.
...
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votes
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Last non-zero digit of n!
Given an integer 1 ≤ N ≤ 1,000,000 as input, output the last non-zero digit of N!, where ! is the factorial (the product of all numbers from 1 to N, inclusive). This is OEIS sequence A008904.
Your ...
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Find the Factorial!
Create the shortest program or function that finds the factorial of a non-negative integer.
The factorial, represented with ! is defined as such
$$n!:=\begin{...
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