To be fair, I used to think like this too, but chatting with multiple large exchanges/brokerages made us realize this was a thing.
> less than 10^15 cents
There are systems that don't work in terms of cents (cf. the examples of issues in many of the comments here), or even in thousandths of a cent, but with significantly more precision.
Literally, in other words:
Where you run into problems then, with 10 ^ n integer scaling, is when n is large. When n is large, you aren't left with sufficient room in the remaining bytes to represent the whole-number part. In trading systems, for instance, you can easily hit 10 ^ 10 to represent fractional traded prices.
Concretely, if you need to scale by 10 ^ 10, then your whole-number part is 2 ^ 64 / 10 ^ 10 = 1,844,674,407, which isn't terribly large.
> less than 10^15 cents
There are systems that don't work in terms of cents (cf. the examples of issues in many of the comments here), or even in thousandths of a cent, but with significantly more precision.
Literally, in other words:
Where you run into problems then, with 10 ^ n integer scaling, is when n is large. When n is large, you aren't left with sufficient room in the remaining bytes to represent the whole-number part. In trading systems, for instance, you can easily hit 10 ^ 10 to represent fractional traded prices.
Concretely, if you need to scale by 10 ^ 10, then your whole-number part is 2 ^ 64 / 10 ^ 10 = 1,844,674,407, which isn't terribly large.