An operation is commutative if you can change the order of the numbers involved without changing the result. Addition and multiplication are both commutative. Subtraction is not commutative: 2 - 1 is not equal to 1 - 2. So my question is what’s the difference between 2 - 1 and 1 - 2?

2-1=1 and 1-2=-1

2-1 = 1 and 1-2 = -1.

So the difference is 2.

If you asking why it is that way, it just IS. It can be deduced logically from how subtraction is defined.

There is no difference between 1-2 and 2-1 if you disregard the + or - in the final answer.

Sometimes when I do calculations on the calculator and I forget which number is the larger, I will end up with a negative answer. I just remember that the answer should be positive. Look at the equation and you can see if the answer should be + or -.

When you subtract one number from another, the order in which you subtract matters. Let's break it down:

To calculate 2 - 1, you start with the number 2 and subtract 1 from it. This gives you a result of 1. So, 2 - 1 = 1.

On the other hand, to calculate 1 - 2, you start with the number 1 and subtract 2 from it. However, since you're subtracting a larger number from a smaller number, you end up with a negative result. So, 1 - 2 = -1.

In summary, the difference between 2 - 1 and 1 - 2 is that the former (2 - 1) gives a positive result of 1, while the latter (1 - 2) gives a negative result of -1. This demonstrates that subtraction is not commutative.