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fac(3) =
6
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BYJUS
byjus.com › maths › factorial
Factorial
In short, a factorial is a function that multiplies a number by every number below it till 1. For example, the factorial of 3 represents the multiplication of numbers 3, 2, 1, i.e.
Published   October 6, 2021
Views   1K
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CalculatorSoup
calculatorsoup.com › calculators › discretemathematics › factorials.php
Factorial Calculator n!
Factorial of 10 10! = 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 = 3,628,800 ... A factorial is a function that multiplies a number by every number below it. For example 5!= 5*4*3*2*1=120.
People also ask

What is the meaning of 5 factorial?
The meaning of 5 factorial is that we need to multiply the numbers from 1 to 5. That means, 5! = 5 × 4 × 3 × 2 × 1 = 120.
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byjus.com
byjus.com › maths › factorial
Factorial
What is the symbol of factorial?
The factorial function is a mathematical formula represented by an exclamation mark “!”. For example, the factorial of 8 can be represented as 8! and it is read as eight factorial.
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byjus.com
byjus.com › maths › factorial
Factorial
What is the value of 7!?
The value of 7! is 5040, i.e. 7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5040.
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byjus.com
byjus.com › maths › factorial
Factorial
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Wikipedia
en.wikipedia.org › wiki › Factorial
Factorial - Wikipedia
1 week ago - The word "factorial" (originally ... that this name refers to are the terms of the product formula for the factorial. ... {\displaystyle n!=1\cdot 2\cdot 3\cdots (n-2)\cdot ......
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Vedantu
vedantu.com › question-answer › what-does-3-factorial-mean-class-10-maths-cbse-602f3ddfd7a10e4df29a6b46
What does 3 factorial mean class 10 maths CBSE
January 17, 2026 - Hint: In the given question, we have been asked to find the factorial of a given number i.e. 3. Factorial is the product of all the numbers which are less than or equal to that given number, numbers should be only positive integers such that ‘n’ factorial means product of all the numbers ...
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Unacademy
unacademy.com › question & answer › mathematics questions › what does 3 factorial mean?
What does 3 factorial mean?
September 5, 2022 - It is denoted by an exclamation mark or symbol ‘!’. The general formula of factorial is n!=1×2×3×4×⋯×(n-1)×n Factorial of 3 means, the multiplication of natural numbers from 1.to 3
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Quora
quora.com › What-is-factorial-of-3
What is factorial of (-3)? - Quora
Answer (1 of 3): As 0! and 1! = 1 , 2! = 2, 3! = 6 and so on Can we not have -1! = -1 -2! = 2 = -1 X -2 -3! = -6 = -1 X -2 X -3 -4! = 24 = -1 X -2 X -3 X -4 -5! = -120 = -1 X -2 X -3 X -4 X -5 ...and so on?
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CoolConversion
coolconversion.com › home › math & numbers › factorial calculator › 3 factorial (3!) | factorial calculator
What is the factorial of 3 ?
The factorial symbol is the exclamation mark (!). If n is a natural number greater than or equal to 1, then · n! = n x (n - 1) x (n - 2) x (n - 3) ... 3 x 2 x 1 · If n = 0, then n! = 1, by convention.
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freeCodeCamp
freecodecamp.org › news › what-is-a-factorial
What is a Factorial? How to Calculate Factorials with Examples
August 3, 2022 - Practically speaking, a factorial is the number of different permutations you can have with n items: 3 items can be arranged in exactly 6 different ways (expressed as 3!).
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Math is Fun
mathsisfun.com › numbers › factorial.html
Factorial Function !
The formula is 7!(7−3)! = 7!4! ... That was neat. The 4 × 3 × 2 × 1 "cancelled out", leaving only 7 × 6 × 5. And: ... So there are 210 different ways that 7 people could come 1st, 2nd and 3rd. ... Factorials also appear in probability and statistics, such as calculating lottery odds. As you can see, it gets big quickly. If you need more, try the Full Precision Calculator. ... There are 52! ways to shuffle a deck of ...
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ZeptoMath
zeptomath.com › calculators › factorial.php
3! - Factorial of 3
To determine the number of zeros at the end of a factorial, recursively divide the number by 5 until the quotient is less than 5, and sum the results after applying the greatest integer function. The greatest integer function (usually denoted by brackets) is the rounded down integer of a value. For example, [5] = 5, [4.5] = 4, [-4.5] = -5. For example, the number of trailing zeros in 3!
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Hacker News
news.ycombinator.com › item
Do you know what a factorial is? 3 factorial is written as 3! and is defined as ... | Hacker News
September 9, 2022 - That’s easy. What about 100! Or 124! Obviously you could calculate that by multiplying all the numbers but that’s slow. A quicker way is to use Ramanujan’s formula which will give you an answer with much less calculation. The catch is that the answer may not be exactly correct, just a ...
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Reddit
reddit.com › r/explainlikeimfive › eli5: what is a factorial and how does it work
r/explainlikeimfive on Reddit: ELI5: What is a factorial and how does it work
December 31, 2024 - For example, if 5 people run in ... 3 people can finish third, any of the 2 remaining people can finish fourth, and the last remaining person finishes last. So there are 5! = 5x4x3x2x1 = 120 different possible race results. ... Another use of factorials has to do with irrational numbers (i.e numbers that cannot represented as the ratio of two integers) such as pi and e. You can approximate those values using formulas that incorporate factorials. ... A factorial is a number ...
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askIITians
askiitians.com › forums › 10-grade-maths › what-does-3-factorial-mean-25_480480.htm
What does 3 factorial mean? - askIITians
July 28, 2025 - When we talk about "3 factorial," we are referring to a mathematical operation that involves multiplying a series of descending natural numbers. The notation for factorial is represented by an exclamation mark, so 3 factorial is written as 3!.
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Quality Gurus
qualitygurus.com › what-is-a-factorial
What is a Factorial? | Quality Gurus
April 24, 2023 - A: The factorial of 2 (2!) is 2 × 1 = 2, as there are two ways to arrange two items. ... A: The factorial of 3 (3!) is 3 × 2 × 1 = 6, as there are six ways to arrange three items.
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Reddit
reddit.com › r/learnmath › what does factorial mean realistically ?
r/learnmath on Reddit: What does factorial mean realistically ?
June 12, 2020 -

Never bothered to understand maths ever, and am now reading cryptography as a hobby in spare time, so help me guys please.

I got that the factorial means just the product of numbers , eg : 4! = 4 × 3 × 2 × 1

Lets say, take a letter for english alphabet and replace it with another random letter for eg :

A = I B = H

,then the books says the decryption keys will be equal to 26 factorial or 26! (since there are 26 letters in english alphabet)

This doesnt' make any sense whatsoever , if the question is too basic please point to another sub if possible. I googled the shit out of it and still don't get it.

Top answer
1 of 10
98
It is describing how many ways that a substitution key can be created. Walk through it this way. Assume that we start with A. What alphabet replaces 'A'. It could be anything from A to Z. So there are 26 choices of a substitute. OK. Let's for the purpose of this example say 'A's will be replaced by 'K'. Now go to B. What alphabet replaces B? Since we already assigned K to replace A, there are only 25 alphabets to choose from. By the time you get to Z, there will be only one unassigned substitute. So how many keys total? There are 26 choices from our starting point, then 25, then 24 all the way to 1. Therefore there are 26 * 25 * 24 *... * 1 ways of creating a unique key and this is called 26! from the definition of factorials.
2 of 10
7
What the book is saying is that "there are 26 factorial possible keys for a simple substitution". To see why this is true let's go through part of the process: What will A be changed into? Well there are 26 possibilities. We could say that A doesn't change or we could say it changes into any other letter. Let's pick L and say A -> L is one of our rules. Now, what will B get changed into? There are only 25 possibilities left if we want the cipher to work. B can get changed to any letter except L because we've already decided that A turns into L. If B became L then when decoding there would be no way to know if L meant A or B. So let's make the rule B -> K. For C there are only 24 possibilities, following the same logic. And so on down to Z which will have only one option.
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Stat Trek
stattrek.com › online-calculator › factorial
Factorial Calculator
The first card chosen can be any of 13 spades; the second, any of the remaining 12 spades; the third, any of the remaining 11 spades; and so on. Since we want to know how 13 cards can be arranged, we compute the value for 13 factorial. 13! = (13)(12)(11)(10)(9)(8)(7)(6)(5)(4)(3)(2)(1) = 6,227,020,800 Note that the above calculation is a little cumbersome to compute by hand, but it can be easily computed using the Factorial Calculator.
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Answers
math.answers.com › math-and-arithmetic › How_do_you_solve_the_factorial_of_3
How do you solve the factorial of 3? - Answers
A factorial is a whole number multiplied by all the whole numbers less than that number. So 3 factorial (written as 3!) is 3 times 2 times 1=6 ... To solve factorial expressions, first understand the definition of a factorial: for any positive ...