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Given an octal number as input. Now, write a Kotlin program to convert Octal number to Decimal Number.

Input: 20 Output: 16

Input: 324 Output: 212

Input: 1000 Output: 512

## 1. Program to Convert Octal to Decimal

###### Pseudo Algorithm

- Initialise a variable
**decimalNum**, that stores equivalent decimal value, with 0 - Extract each digit from the octal number.
- While extracting, multiply the extracted digit with proper base (power of 8).
- For example, if octal number is 110, decimalNum = 1 * (8^2) + 1 * (8^1) + 0 * (8^0) = 72

Sourcecode –

import java.util.* fun main() { val read = Scanner(System.`in`) println("Enter n:") val octalN = read.nextLong() var decimalNum: Long = 0 if(checkOctalNumber(octalN)) { var n = octalN var base = 1 while (n != 0.toLong()) { val lastDigit = n % 10 n /= 10 decimalNum += lastDigit * base base *= 8 } println("Equivalent Decimal : $decimalNum") } else { println("$octalN is not a octal number") } } private fun checkOctalNumber(octalNum: Long): Boolean { var isOctal = true var n = octalNum while (n != 0.toLong()) { val lastDigit = n % 10 if(!((lastDigit >= 0.toLong()) || (lastDigit <= 7.toLong()))) { isOctal = false break } n /= 10 } return isOctal }

When you run the program, output will be –

Enter n: 2432 Equivalent Decimal : 1306

###### Explanation:

Here, we have created an object of Scanner. Scanner takes an argument which says where to take input from.

**System.`in`** means take input from standard input – Keyboard.

**read.nextLong()** means read anything entered by user before space or line break from standard input – Keyboard.

We stored value entered by user in variable **octalN**.

At first, we checked if entered value is octal or not.

If NO, we print a message ” number is not octal number”.

- We use
**checkOctalNumber**function to check if number is octal or not. If any digit in number is neither 0 nor 1, then, it is not octal number.

If Yes, we start converting those number into decimal –

- variable
**base**contains power of 8 to the position at which current last digit we have in**lastDigit** - Decimal value is sum of
**lastDigit * (power of 8 to the position at which current lastDigit is at)** - For example,

octalN = 110decimalN = 1 * (8 ^ 2) + 1 * (8^1) + 0 * (8 ^ 0) = 72

Thus, we went through Kotlin Program to Convert Octal Number to Decimal Number.

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