I’m not an expert and I’ve only just started learning so my answer is in simple terms. but i think the original question was to do with when would we use a mathematical operator. My logic says when you want to change the value of a variable based on a calculation. Maybe a better question is why would you use it?
My suggestion would be this forum for example, every time someone replies to a question, a counter tells you how many replies. So I’m assuming that the the counter waits for a click on the reply button and when it hears one, the code does something like this
reply = reply + 1;
reply += 1;
Another use might be in calculating score in a game.
For example if you hit the red ball worth 5 points then something like an if statement could be use and within that you would have
A different if statement might be used for the blue ball which scores 10 points in which case that statement would have within it
score =+ 10;
In my imaginary game you have to avoid hitting the butterflies but if you do hit then another if statement would have within it
Let’s say when you reach a score of zero or less, it’s game over.
Anyway, that’s how I see a use for them.