Zero has been used since ancient Sumerian society to represent nothing. Modern oval shape appeared in Arabic in late 700s. Zero is now commonly used as an integer in math
Modern zero is written as circle, ellipse or rounded square/rectangle. Typefaces often make capital O more rounded than digit 0. IBM 3270 introduced dot-centered zero option. Some early printers used unornamented zero with tailed capital O
Both "zero point zero one" and "point zero one" are correct. "Point Oh one" is commonly used. "Point zero one" is slightly more accurate
Dionysius Exiguus introduced AD era in 525 to avoid Diocletian era. Bede popularized AD era in 731, using "ante incarnationis dominicae tempus". No year zero exists in AD calendar system, 1 BC followed by AD 1. Bede's dates show 106 years between BC and AD without zero
Zero is distinct from positive and negative numbers in neutral context. Zero is the middle value of the trichotomous real numbers line. Zero is equal to both negative (-1⋅|arg|) and positive (+1⋅|arg|)
Zero is an integer, but neither positive nor negative. Zero is a whole number without fractions or decimals. Zero sits between positive and negative numbers on the number line