Can someone explain how the commas work for the f string?

Question

So I know when I type

print(f'{balance:2,.2f}')

it's going to put the commas in the right spot for my numbers, but I would like to know why that is. I know that the 2f makes the decimal fixed at two places to the right, but why does the comma go over 3 to the left of the decimal and every 3 after?

Answer 1

The comma (",") in the f-string works as a thousand separator. So if your number is going to be million, billion, or even trillion, it will still separate each group of three numbers by a comma

Answer 2

Because thats the convention for commas in big numbers. Theres no way to change that, its always 3.