**Q: **Is a 0 used as a placeholder in place value systems? ¶

**A: **Yes.

**Q: **Is a 0 undefined? ¶

**A: **Yes, because 0 has no multiplicative inverse , a consequence of the previous rule.

**Q: **Is a 0 sometimes used to denote an initial object of a category? ¶

**A: **Yes.

**Q: **Is a 0 usually written as a circle or ellipse? ¶

**A: **Yes.

**Q: **Is a 0 converted into the null pointer at compile time when it appears in a pointer context? ¶

**A: **Yes, and so 0 is a standard way to refer to the null pointer in code.

**Q: **Was a 0 identified before the idea of negative things? ¶

**A: **Yes, or quantities less than zero, was accepted.

**Q: **Is a 0 a natural number? ¶

**A: **Yes, and then the only natural number not to be positive.

**Q: **Is a 0 neither positive nor negative? ¶

**A: **Yes.

**Q: **Is a 0 used either exclusively? ¶

**A: **Yes, or not at all, to avoid confusion altogether.

**Q: **Is a 0 often used for dialling out of a company network or to a different city or region? ¶

**A: **Yes, and 00 is used for dialling abroad.

**Q: **Is a 0 given to one of the drivers of the team that the reigning champion won the title with? ¶

**A: **Yes.

**Q: **Is a 0 an identity element with respect to addition? ¶

**A: **Yes.

**Q: **Is a 0 the smallest non-negative integer? ¶

**A: **Yes.

**Q: **Is a 0 defined to be the empty set? ¶

**A: **Yes.

**Q: **Is a 0 neither positive nor negative and is usually displayed as the central number in a number line? ¶

**A: **Yes.

**Q: **Is a 0 the integer immediately preceding 1? ¶

**A: **Yes, Zero is an even number, because it is divisible by 2 with no remainder.

**Q: **Is a 0 the lowest ordinal number? ¶

**A: **Yes, and corresponding to the empty set viewed as a well-ordered set.

**Q: **Is a 0 the cardinality of the empty set: if one does not have any apples? ¶

**A: **Yes, and then one has 0 apples.