QUOTE (Lanlaorn @ Aug 6 2010, 01:56 PM)
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Actually no the Cyberware suites use the same (multiplicative) model. The game is 100% consistent on which you should use and I don't know where this contradicting opinion comes from. With regards to which is simpler, well IMO multiplying is just intuitively obvious so it's far more complicated (for me) to first add up all the multipliers.
And honestly this is how things work in real life too. If the store has a half off sale and in addition you have a coupon for 50% off they are not going to give you the thing for free. You're going to be paying 25% of the base. Similarly the sales tax will be multiplied against the discounted price, if it was additive you would pay the tax of the full, original price.
Funny, the book clubs I've been a member of over the years have always added the discount rates together before applying them to the base price.
Back when I worked at Waldenbooks, the usual discount fare was 25% on certain things and club members got an additional 10%. If you added the discount amounts on the reciept, they came to 35% of the original price.
So yes, even businesses do follow this.
Mathmatically, if I have a base value with a series of modifiers, the modifiers are added together before being applied to the base value.
X * (A+B+C) = Total
Back when Implant Surgery was still able to affect the Essence used (SR1 & SR2), this was the method of determining the discount. Which made it all the more important to get an excellent surgeon to implant your Beta grade stuff. Getting the good stuff was only one part.
But back to your example. The source of the discount is different than the source of the tax. The rules regarding the tax are in regards to the final sale price at the time of checkout. That tax does not care what the original price was. It only cares about the final sales price.
Thus your tax example falls short showing what you intend.
As for the 50% off coupon, those are typically restricted with verbiage that states it cannot be combined with any other offer or that it only applies to the subtotal on that item/shopping cart.
The rules for such things within SR4(A) do not come with those stipulations. Thus it is perfectly reasonable to follow established precendent (from earlier editions no less) and go with price modifiers being addditive before being multiplied against the base price.