posted by gutDifferential equations. Most of my math classes were way harder than business, and Real Analysis told me "you're done in math", but DE was a joke.
I do agree that DifEQ was the easiest of the 2 year calculus series (Calc 1/2/3 then DifEQ).
Yes you needed calculus first but it was far easier at the time of taking it than the 3 calculus classes.
Partial differential equations, advanced calculus, and real analysis however are a different ballgame.