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Kotlin Program to Find Factorial of a number
In this article, we will understand how to find the factorial of a number. Factorial of a number is the product of itself with each of its lower numbers.
Below is a demonstration of the same −
Suppose our input is
Enter the number : 5
The desired output would be −
The factorial of 5 is 120
Algorithm
Step 1 − Start
Step 2 − Declare three integers: input, myResult and i
Step 3 − Hardcode the integer
Step 4 − Run a for-loop, multiply the number with its lower number and run the loop till the number is reduced to 1.
Step 5 − Display the result
Step 6 − Stop
Example 1
In this example, we will calculate the factorial of a number in Kotlin using for loop. First, declare and set the input for which we will find the factorial later −
val input = 5
Set a variable wherein the factorial result will be displayed
var myResult: Long = 1
Now, use the for loop to calculate the Factorial:
for (i in 1..input) { myResult *= i.toLong() }
Let us now see the complete example to calculate the Factorial of an integer −
fun main() { val input = 5 println("The input value is defined as $input") var myResult: Long = 1 for (i in 1..input) { myResult *= i.toLong() } println("The factorial of $input is $myResult") }
Output
The input value is defined as 10 The factorial of 10 is 120
Example 2
In this example, we will calculate the factorial of a number in Kotlin
fun main() { val input = 5 println("The input value is defined as $input") printFactors(input) } fun printFactors(input: Int) { var myResult: Long = 1 for (i in 1..input) { myResult *= i.toLong() } println("The factorial of $input is $myResult") }
Output
The number is 5 The factorial of 5 is 120
Example 3
In this example, we will calculate the factorial of a number using Recursion in Kotlin −
fun main() { val input = 7 val res: Long println("The input value is defined as $input") res = factorialFunc(input) println("
Factorial = $res") } fun factorialFunc(input: Int): Long { return if (input == 1) input.toLong() else input*factorialFunc(input-1) }
Output
The input value is defined as 7 Factorial = 5040