PowerShell Script to Convert Decimal to Binary Number

Use the PowerShell expression [Convert]::ToString(decimalNumber, 2) to convert a decimal number to its binary string representation.

Examples

Input0

Output0

Input10

Output1010

Input255

Output11111111

How to Think About It

To convert a decimal number to binary, think of dividing the number by 2 repeatedly and recording the remainder each time. These remainders, read in reverse order, form the binary number. PowerShell provides a built-in method to do this conversion easily by specifying base 2.

Algorithm

1

Get the decimal number input.

2

Use a built-in method to convert the number to a binary string with base 2.

3

Return or print the binary string.

Code

powershell

param([int]$decimalNumber)
$binaryString = [Convert]::ToString($decimalNumber, 2)
Write-Output $binaryString

Output

1010

Dry Run

Let's trace converting decimal 10 to binary using the script.

1

Input decimal number

decimalNumber = 10

2

Convert decimal to binary string

[Convert]::ToString(10, 2) returns '1010'

3

Output binary string

Print '1010'

Decimal	Binary String
10	1010

Why This Works

Step 1: Using built-in conversion

PowerShell's [Convert] class has a method ToString that converts numbers to strings in any base, here base 2 for binary.

Step 2: Passing base 2

Passing 2 as the second argument tells the method to convert the decimal number into binary format.

Step 3: Output as string

The method returns the binary number as a string, which can be printed or used further.

Alternative Approaches

Manual division and remainder

powershell

param([int]$decimalNumber)
$binary = ''
if ($decimalNumber -eq 0) { $binary = '0' }
while ($decimalNumber -gt 0) {
    $remainder = $decimalNumber % 2
    $binary = $remainder.ToString() + $binary
    $decimalNumber = [math]::Floor($decimalNumber / 2)
}
Write-Output $binary

This method shows the manual process but is longer and less efficient than using the built-in method.

Using ConvertTo-String with base parameter (PowerShell 7+)

powershell

param([int]$decimalNumber)
$binaryString = $decimalNumber.ToString(2)
Write-Output $binaryString

This uses the .NET ToString method on the integer directly, available in newer PowerShell versions.

Complexity: O(log n) time, O(log n) space

Time Complexity

Conversion depends on the number of bits in the decimal number, which is proportional to log base 2 of the number.

Space Complexity

The binary string length grows with the number of bits, so space is proportional to log base 2 of the input number.

Which Approach is Fastest?

Using the built-in [Convert]::ToString method is fastest and simplest compared to manual division.

Approach	Time	Space	Best For
[Convert]::ToString	O(log n)	O(log n)	Quick and reliable conversion
Manual division	O(log n)	O(log n)	Learning and understanding conversion process
.ToString(2) method	O(log n)	O(log n)	Modern PowerShell versions, concise code