Hey, this is a stupid question but I want to settle it. Here's how I do d% and I want to make sure its correct. I'm talking about for concealment in combat, say the defender has a 20% concealment. Since defender always rolls concealment and high rolls are always good, if the die comes up 81-100 the attack misses. This is done after the attacker rolls to hit.
doesn't really matter whether 1-20 or 81-00 misses, but establish that before the roll is made; also, make sure that you're use an actual d% (0o-9o notation) lest the roller decides on the fly that that thar 19 was a 91. That is, call which die is the tens digit before rolling.