3-3*6+2= on one calculator it says 2 and on the other it says -13 which is correct if there are NO parenthisis?

2...

The answer is -13 by using PEMDAS.

Let's review

Parentheses

Exponents

Multiplication

Division

Addition

Subtraction

Now, let's look at the problem.

3-3*6+2

There are no parentheses or exponents, but there is multiplication. Let's just get that done. 3*6=18

3-18+2

3-18 is -15

-15+2

-15+2 is -13, so -13 is your answer.