[snowman]

Solve a differential equation with a calculator. Just go ahead and try. You can solve differential equations numerically, but you have to write a computer program to do so.

Derive the s. wave equations with a calculator. I don't think so. Solve the particle in a box problem using a calculator, or a pulsed system without LaPlace transforms or Fourier series. Calculators are not evil, they are a tool. THey can be used in math but they are NOT math. Math is a language, not a manipulation of just numbers.