Budget merchandise spending at an event.
Merch stands price in whole items, so a budget only matters in units it can actually buy. Dividing the budget by the shirt price and flooring the result gives what you can walk away with, and checking whether a shirt each fits first is the decision most groups face. Whatever survives that goes to cheaper items, which is why the leftover is converted into posters rather than left as an abstract balance.
Whole items affordable
Shirts affordable = floor(merch budget / shirt price)
Leftover allocation
Leftover = budget - shirt price x people; posters = floor(leftover / poster price)
Because a merch stand will not sell you 1.7 shirts. Rounding up would produce a plan the budget cannot pay for.
Often cheaper per item, but tour-exclusive designs and the queue-free convenience are what people are paying the venue premium for. Compare with shipping included.