I cross my sevens, slash my zeros, and use a hook on lowercase T to avoid confusion with plus signs. I think I developed the hook-T habit in college math classes.

I didn’t even think about that one, I do that as well, and for the exact same reason! That’s too funny.

That's good, because the "O" should never be dotted. You use slash OR dot for zero, unless you vaguely remember them both as useful for disambiguating but forgot that both marks are for zero and vary by typeface. Mostly dotted zero was just during the dot matrix era. I wouldn't mind being shown counter examples.

I cross my sevens!

I'll consider starting to slash my zeros. Seems legit.

Øh, that isn't ideal for Danes, Norwegians or people who regularly deal with empty sets.

What I had done sometimes when writing slashed zero by a pencil and needed the disambiguation (which is not that common in my writing but it does happen sometimes that it will be important), is for the slash the other way for zero, to avoid being confused with slashed O or the symbol for empty sets. Atkinson Hyperlegible font (mentioned in another comment) also works that way, too; the slash for zero is the other way than the slashed O in languages that use that.

Fair enough, but I was whittering on about English and not Dansk or Norsk. The empty set should be obvious from context.

In india its considered bad omen to slash 7s.

We are trying to summon a Leviathan here.