0×81

0×81 is an arithmetic expression that denotes the product of zero and eighty-one. In standard arithmetic, any number multiplied by zero is zero, so 0×81 = 0. This result holds in integers, real numbers, and complex numbers, reflecting the zero property of multiplication.

The expression also illustrates a fundamental algebraic rule: the zero property. It is consistent with the distributive law, since a×(b+c) = a×b + a×c; when a = 0, both sides equal 0 regardless of b and c. The property underpins many simple calculations and proofs in algebra.

In computing and typography, the symbol × is commonly used to indicate multiplication in math notation. In many programming languages, however, the multiplication operator is represented by an asterisk (*) rather than ×. The string 0×81 is therefore a mathematical notation, whereas 0x81 (without the times sign) is a common hexadecimal literal in several programming languages and denotes the decimal value 129, not the product 0×81.

Outside decimal notation, the product 0×81 remains 0 in any base, and in modular arithmetic, 0×81 ≡ 0 (mod m) for any modulus m. The expression is often cited as a basic example of the impact of a zero factor in multiplication.