If you have a C program where no matter if you calculate the output from left to right or right to left it calcuates the same output, but when you calculate the output from left to right and right to left with paper and pencil and you get a different output. Why is that?
I think what he's trying to say is that the computer will calculate the output in order of BEDMAS: Brackets, Exponents. Division, Multiplication, Addition, Subtraction.