# Laying Down The Law

The significance of Brahmagupta’s laws is that they treat zero as a number, not just a place holder, and negative number s are treated as numbers, not numerical outcasts to be ignored.

1. A zero added to a number is the number.
2. A zero subtracted from a number is the number.
3. A number times zero is zero.
4. A negative minus zero is a negative.
5. A positive minus zero is a positive.
6. Zero minus zero is zero.
7. A negative subtracted from zero is a positive.
8. A positive subtracted from zero is a negative.
9. The product (what you get when you multiply numbers) of zero multiplied by a negative of positive is zero.
10. The product of zero multiplied by zero is zero.
11. The product or quotient (what you get when you divide numbers) of two positives is one positive.
12. The product or quotient of two negatives is one positive.
13. The product or quotient of a negative and a positive is a negative.
14. The product or quotient of a positive and a negative is a negative.