I may suggest to overthink the following line of the article for mathematical correctness and easier understanding:
"Max damage reduction = Icon stat damage.png Damage * (1 - Icon stat armour.png Armour * random(0.5, 1))%"
Firstly this expression does neither express the damage reduction nor just the maximum, even if it did. It shows how the part of the damage, which is affected by armor, varies in correspondance to armour. It does not show the damage reduction itsself, which is soley expressed by the last part of the term.
Secondly there is a typo in the formula, as the %-sign at the end is outside of the brackets. Even if you interpreted it as a multiplication with 1/100, you would need to respect the distributive property, but then it would get wrong.
I feel bad correcting it on my own as I dont want to degrade someone's work, but if you want to hear my proposal:
Min/Max Damage Reduction: (1 - Armour/100 * random(0.5, 1) )
Salut Philkingz aka M.D.Grunt