That said, I can see an argument that an RPN calculator "trivializes" the assignment compared to an infix calculator, especially if the latter was supposed to do order-of-operations.
But that experience did teach me a valuable lesson -- always follow the specifications as close as possible, don't try to innovate (unless working on your own projects). And, I've learned to spot (and explain) contradictory / intractable specifications up front.
I am personally doubly surprised as GP to find two people in a discussion about Computer Science at a college level that have not heard of RPN before. For what it's worth!
If you have taken an introduction to the Unix/Linux shell, you most probably saw the dc command.