I read that different cultures have different ways of grouping digits before the decimal point for readability e.g. 1234567890 can be grouped as 1 234 567 890 (English), 12 3456 7890 (Chinese) or 1 23 45 67 890 (Indian), but is there an established convention for grouping digits of a real number after the decimal point for readability e.g. should 3.14159265358979 be grouped as 3.141 592 653 589 79, 3.14159 26535 8979 or something else?
The only convention I have come across is that many publications of mathematical vales tend to group the digits after the decimal point in blocks of 5, so that Pi would appear as 3.14159 26535 89793 ...
You can see examples such as this on Wikipedia, but I have never heard of any official or widespread convention about this.
One thing I found is the Swift programming example about decimals Numeric Literals
let oneMillion = 1_000_000 let justOverOneMillion = 1_000_000.000_000_1