# Pipe find specifid string into systeminfo output so only that line is exported
systeminfo | find "System Boot Time" > SystemBootTime.txt

#Insert file contents into new variable
$BootTimeString = Get-Content .\SystemBootTime.txt

#Edit contents of the previous variable to make it ead like a date and make a new variable from it
$BootTimeValue = $BootTimeString.TrimStart("System Boot Time:          ") -replace '[,]'

#force the fomatting of the previous variables content into a datetime type and place in a new variable
$BootTime = [datetime]::ParseExact("$BootTimeValue", 'dd/MM/yyyy HH:mm:ss', $null)

#Get the current time
$Now = Get-Date

#Compare the boot time with the current time and format the output into total minutes and current seconds.
NEW-TIMESPAN -Start $BootTime -End $Now | Select-Object @{Label="Minutes";Expression={[math]::Floor($_.TotalMinutes)}}, Seconds