This site helped me figure it out.
This is what you do to get that overbar on a 6 (or any number or letter):
{ EQ \O(6,¯) }
What you need to know:
- Works on MS Word and probably other MS products, but NOT html
- Typing the brackets {} won't work, you have to hit [Ctrl] + [F9]
- To get the ¯, you hold down the [Alt] key and type 0175 on the keypad (not the top numbers)
- The O is the letter O, not the number zero (0)
- Finally, to toggle between FORMULA look and actual 6 with an overbar, hit [Alt] + [F9]
- To format the overbar separately from the character, format the ¯ in the formula mode
Not too difficult, but not as easy as "insert symbol".