As illogical as it may seem, calculators have two major types of logic which change the results you may get from inputting several numbers.

The first kind of calculator logic is Serial Logic.

That is, the calculator will operate all terms serially.

The arguments 3 + 3 * 5 = will return 45 on a Serial Logic Calculator, because the calculator only handles two numbers at once. It treats it as such: 3 + 3 equals 9. New Problem, first argument 9. 9 * 5 = 45.

This would be incorrect in algebra if the problem was "3 + 3 * 5 = x (What is x?)" because that would not follow The Order of Operations, which when applied here states that, multiplication takes place before addition. Therefore, with a serial logic calculator, you must follow the order of operations yourself, multiplying 3 * 5 first then adding 3.

On an algebraic logic calculator, imputting the string of arguments 3 + 3 * 5 = will return 18, because the algebraic logic calculator treats all numbers as part of the same expression.