[xyproto]

Space is also confusing! Then it looks like two separate numbers.

Underscore (_) is already used as a decimal separator in programming languages and Mathematics should just adopt it, IMO.

[awakeasleep]

A competing format to simplify things?

[bhaak]

A competing format that is understandable to probably everybody.

An ISO 8601 date is also comprehensible to anybody even if they never seen it before and have to figure it out themselves.

[ultratalk]

https://xkcd.com/927/

[wvbdmp]

You mean thousands separator, yes? Agreed, it’s annoying when languages don’t have this feature.

[xyproto]

Ah yes, thousands separator.

[wongarsu]

A thin non-breaking space also clears up the confusion without the visual clutter of the underscore. It's just inconvenient to use