Just imagine the world where we have CAPITALIZED DIGITS.

— Hey, are our primary keys begin with capital digit or not?

— Should we have our years all capitals, only with first digit capital or all lowercase?
— I don't know, maybe it should be camelcase.

— Fuck! That new guy's code pushes unix time with first digit capital!

Kind of ashamed to say I have in fact tried to do that once, when extremely tired.

Now, with that being said, a close analog, perhaps, may be the different sets of numerical kanji used for banking in China and Japan to ensure absolute clarity regarding the amount, and preventing people from changing it by just adding a line, etc. (kind of like writing the digits and then spelling it out in English).

First section of this article has some great info, and actually makes the comparison to “capital numbers”: https://en.m.wikibooks.org/wiki/.../Numbers

(Note: DevRant seems to be butchering the link when I test it. Append /Numbers to the link to get to the right article.)