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

AmitDiwan

Updated on: 13-Oct-2022

1K+ Views

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