I sometimes add a space to help make the number more readable. Like the price for a share of S.MPOE is something like 0.00072828 bitcoins, you could write that as  0.000 728 28  to make it more readable. The problem with that is the space makes it hard to know where the number ends. An alternative would be to use ` (on my keyboard it is on the same key as the tilde, ~, but I never use it for anything), so the price would be 0.000`728`28 which is also more readable than having no separators. What is that mark even called?

If you want to have lots of precision in your database or whatever, you could write numbers like 11`258`124.000`999`94 using the tick mark before and after the decimal separator.

` is also commonly called a backtick.  I've even seen it called that by non-unix/non-technical people to disambiguate the thing on the keyboard and the thing in ASCII from a "proper" grave.  In fact, I'm not sure that it is even technically a "grave" when it isn't attached to a vowel.

Similar problems come up with quotation marks.  ASCII has "single quote" and "double quote", but again, they aren't "proper", so some people call those versions by those names to distinguish them from actual real "quotation marks".