BossShop Price Calculation

Calculation support: Every numerical price type supports simple calculations with raw numbers (excluding placeholders). on https://www.spigotmc.org/wiki/bossshoppro-pricetypes/
What is the meaning of placeholders above?
"calculations with raw numbers"
did calculator have a variable/symbols which make random price or increase/decrease on the price? It'll be very helpfull is there's one or some..

Did I can make a price which contain between? like min-max price after negotiation?
for the ex I got drop item from boss name Abyssal Sword
the price is between 258-312, the shop will randomize price between that number, so it'll out "x" number which will be the price for the item (after sold) the player can't show the final price if he/she not sell the item.
Thanks.