 # Kotlin Program to Convert Binary Number to Decimal and vice-versa

Visit this page to learn how to convert binary number to decimal.

## Example 1: Program to convert binary number to decimal

``````fun main(args: Array<String>) {
val num: Long = 110110111
val decimal = convertBinaryToDecimal(num)
println("\$num in binary = \$decimal in decimal")
}

fun convertBinaryToDecimal(num: Long): Int {
var num = num
var decimalNumber = 0
var i = 0
var remainder: Long

while (num.toInt() != 0) {
remainder = num % 10
num /= 10
decimalNumber += (remainder * Math.pow(2.0, i.toDouble())).toInt()
++i
}
return decimalNumber
}``````

Output

`110110111 in binary = 439 in decimal`

Visit this page to learn, how to convert decimal number to binary.

## Example 2: Program to Convert Decimal to Binary

We can use the `Integer.toBinaryString()` method to convert a decimal number to binary.

``````fun main(args: Array<String>) {
val num = 19

// converting decimal to binary
val binary = Integer.toBinaryString(num)
println("\$num in decimal = \$binary in binary")
}
``````

Here's the source code to convert a decimal number to binary manually.

## Example 3: Convert decimal number to binary Manually

``````fun main(args: Array<String>) {
val num = 19
val binary = convertDecimalToBinary(num)
println("\$num in decimal = \$binary in binary")
}

fun convertDecimalToBinary(n: Int): Long {
var n = n
var binaryNumber: Long = 0
var remainder: Int
var i = 1
var step = 1

while (n != 0) {
remainder = n % 2
System.out.printf("Step %d: %d/2, Remainder = %d, Quotient = %d\n", step++, n, remainder, n / 2)
n /= 2
binaryNumber += (remainder * i).toLong()
i *= 10
}
return binaryNumber
}``````

When you run the program, the output will be:

```Step 1: 19/2, Remainder = 1, Quotient = 9
Step 2: 9/2, Remainder = 1, Quotient = 4
Step 3: 4/2, Remainder = 0, Quotient = 2
Step 4: 2/2, Remainder = 0, Quotient = 1
Step 5: 1/2, Remainder = 1, Quotient = 0
19 in decimal = 10011 in binary```

Here's the equivalent Java code: Java Program to convert binary to decimal and vice-versa