[Zerot]

Which is the bigger version number? Version 9.9 or version 9.11? Which is the bigger dollar amount? $9.9 or $9.11?

Periods are not always used for the decimal separator but also as a separator for multiple sets of semi-independent numbers.

[umanwizard]

I have never seen someone write $9.09 as $9.9. What country is this common in?

[Zerot]

None. That is the point. 9.9 can be both bigger or smaller than 9.11 depending on context

[samrus]

if someone says "which is the bigger number" with no context you wont assume software version number, lets be real here

also $9.9 is clearly 9 dollars and 90 cents.