Abstract: This paper syggests the power vector and the vector power series. The vector power series is a "Combinatorial Vector Number" which is composed of a real number and a certain vector. Combinatorial rector variable and its functions have an important meaning. They have the fundamental operations of arithemetic too. From the theoretical analysis of functions for a combinatorial vector variable we would would know its function has the derivatives. the necessary and sufficient conditions. These conditions make up the charaders of "Hyperbolic equation" and its integralions.

Key words: power vector, a combinatorial vector number, hyperbolic equation