Disinfectant Calculator

# Released under the GNU General Public License version 3 by J2897.

<#
    Go and grab a bottle of bleach, disinfectant or some other concentrated liquid.
    The bottle will tell you to put in "60ml per 5L" or something like that.
    This script will tell you what percentage that is.
    More importantly, it will tell you how much concentrate to put in for the amount you actually need.
    So if the bottle tells you to put in 60ml per 5L, and you only want 2.5L, it will tell you to put in 30ml instead.
#>

clear

# Figure out the percentage.
[int]$Millilitres = Read-Host -Prompt "How many millilitres of concentrate does the bottle say?"
[int]$LitresL = Read-Host -Prompt "Per how many litres?"
[int]$LitresMil = $LitresL * 1000
[decimal]$Percentage = $Millilitres * 100 / $LitresMil
Write-Host "The percentage of concentrate is: " -nonewline; Write-Host "$Percentage%" -ForegroundColor Yellow
Write-Host "`r"

# Calculate the desired amount.
[decimal]$SolutionL = Read-Host -Prompt "How many litres do you actually require?"
[decimal]$SolutionMil = $SolutionL * 1000
[decimal]$Concentration = $SolutionMil / 100 * $Percentage
[decimal]$Water = $SolutionMil - $Concentration

# Construct the results.
$Results_0 = 'For ' + $SolutionL + 'L mix '
$Results_1 = "{0:N0}" -f [int]$Water + 'ml'
$Results_2 = ' of water and '
$Results_3 = "{0:N0}" -f [int]$Concentration + 'ml'
$Results_4 = ' of concentrate together.'

# Display the results.
Write-Host $Results_0 -nonewline
Write-Host $Results_1 -nonewline -ForegroundColor Yellow
Write-Host $Results_2 -nonewline
Write-Host $Results_3 -nonewline -ForegroundColor Yellow
Write-Host $Results_4
Write-Host "`r"

Write-Host "Press any key to end..."
[void][System.Console]::ReadKey($true)