## Windows PowerShell Maths

PowerShell is very good at understand whether a command in your script should be handled as text or as a number. Incidentally, the more you study PowerShell’s different math techniques, the more reasons you will find to turn to PowerShell rather than VBScript or Excel.

### Topics for PowerShell Maths

For once, I favour the English word maths (plural) because we are dealing with numerous aspects of math calculation.

- Simple Arithmetic Operations in PowerShell
- PowerShell [Math]::Static Methods
- Measure-Object Cmdlet
- Get-Date Cmdlet
- PowerShell’s Concatenator (+)
- PowerShell ‘=’ Sign and -eq Operator
- Counters for Loops $i++

♣

### Review of Basic PowerShell Mathematics

Get started by simply typing numbers at the PowerShell command line. You can use the 4 well-known operators + – * (asterisk) and / (forward slash), try these calculations:

68 + 47

365 -127

38 * 15

22 / 7

### Simple Arithmetic Operations in PowerShell

PowerShell handles basic maths calculations, such as add and multiply with deceptive ease. Try these simple arithmetic computations:

Clear-Host

$1stNum = 22

$2ndNum = 7

Write-Host "Add, Subtract, Multiply and Divide"

Write-Host "———————————–"

$1stNum **+** $2ndNum #**Add** ………. Answer 29

$1stNum **–** $2ndNum #**Subtrac**t … Answer 15

$1stNum ***** $2ndNum #**Multiply** …. Answer 154

$1stNum **/** $2ndNum #**Divide** ……. Answer 3.14285 (pi)

### Putting PowerShell Maths to Work

Suppose you want to test a router connection. We could use ping, but I have chosen Win32_PingStatus. The point is that Microsoft has designed PowerShell so that it can deal with adding 1 to 192.168.1.1.

# PowerShell Ping math script

$i =1

$IPAddress = "192.168.1."

Do { $Ip4th = $IPAddress+ $i

$PingMath = Get-WmiObject Win32_PingStatus -f "Address='$Ip4th'"

$PingMath | Format-Table Address, StatusCode -hideTableHeaders -auto; $i++

}

Until ($i -eq 20)

**Note 1:** A StatusCode of 0 means a successful ping; 11003 is the equivalent of 'Destination host unreachable'.

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### Review of PowerShell [Math]::Static Methods

Thanks to PowerShell accessing .Net Framework, we can perform trickier math operations; observe the static syntax, [Math]::function(). The key point here is we are asking PowerShell to employ functions such as you would use in Excel.

Clear-Host

$1stNum = 22

$2ndNum = 7

Write-Host "[Math]::Round, Truncate and [int]"

Write-Host "———————————–"**[Math]::Round**($1stNum / $2ndNum,2)**[Math]::Truncate**($1stNum / $2ndNum)

[int]($1stNum / $2ndNum)

**Note 2: **Strictly speaking we should use [System.Math], however, the shorter [Math] works just fine. See more on PowerShell’s static math functions.

### Putting PowerShell Maths to Work

In this scenario we are investigating why a disk labelled 1 terabyte was actually only 931 gigabytes.

# PowerShell WMI class to get disk information

$Disk = Get-WmiObject Win32_diskdrive

Foreach ($Item in $Disk){

"{0,-28} {1,-20} " -f `

$Item.Name, $Item.Size}

**Result: 1000202273280 (Bytes)**

Let us employ PowerShell’s [Math]::Round static method to crack the problem. Also observe where we divide by GB (gigabyte)

$Disk = Get-WmiObject Win32_diskdrive

Foreach ($Item in $Disk){

"{0,-28} {1,-20} " -f `

$Item.Name, ([Math]::Round($Item.Size/1GB,2))}

**Result: 931.51 GB (GigaBytes)**

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### PowerShell’s Concatenator (+)

Joining text strings in PowerShell is very easy, just call for the plus sign; you can even combine text strings with numbers. Observe how seamlessly the simple plus (+) sign joins text, numbers and the result of calculations.

The only danger is overthink, looking for extra syntax when all you need is (+)

Clear-Host

"Guy " **+** "Thomas is over " **+** (100-40)

A more likely scenario would be combining fields, for example concatenating values stored in variables.

Clear-Host

$FirstName = "Guy "

$Surname = "Thomas "

$Age = 64

$FirstName **+** $Surname **+** $Age

My next example is more interesting because it uses [System.Datetime] and also the static function [Math]::Truncate.

Clear-Host

$FirstName = "Guy "

$Surname = "Thomas "

$Age = (Get-date) – ([System.Datetime]"24 June 1949")

$FirstName + $Surname **+** [Math]::Truncate($Age.Days/365)

**Note 3:** Trace the $Age variable; once again you can append a number to a text string.

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### PowerShell -eq and ‘=’ Sign

For a purely mathematical calculation PowerShell uses the -eq conditional operator. The only place beginners see the equals sign in PowerShell is when assigning variables.

The -eq operator has a whole family of relatives, such as -ne (not equal), and then also the branch of the family containing greater than and less than, (-gt and -lt).

**Mission: To Find Zero Length Files**Key command: Where-Object {$_.length

**-eq**0}

# PowerShell script to find zero length files in Windows folder

Clear-Host

$FileSource **= **"C:\Windows"

$Empty **=** Get-ChildItem -path $Filesource -Recurse -ErrorAction SilentlyContinue

$Empty | Where-Object {$_.Length **-eq** 0} | Ft FullName, Length -AutoSize

**Note 4:** Observe the use of ‘=’ to declare variables; but -eq for the actual comparison operator.

See much more on PowerShell’s comparison operators »

### Summary: Review of Windows PowerShell Maths

PowerShell always makes an effort to understand whether your code is text or a number. The secret of handling more complex maths functions is to understand [System.Math]:: static functions.

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### See more PowerShell examples of math operations

• PowerShell Maths Index • Windows PowerShell • PowerShell Splatting

• PowerShell Math • Comparison Operators • PowerShell Measure Object • Measure Command

• PowerShell Tutorials • Syntax • Pipeline • PowrShell Quotes • Free WMI Monitor

Please email me if you have a better example script. Also please report any factual mistakes, grammatical errors or broken links, I will be happy to correct the fault.