In the numeration system commonly used in scientific notation, the real number that is raised to a power denoted by the exponent and then multiplied by the coefficient to determine the value of the number represented without the use of exponents. Note: An example of a base is the number 6. 25 in the expression 2. 70 × 6. 251. 5 42. 19. The 2. 70 is the coefficient and the 1. 5 is the exponent. In the decimal numeration system, the base is 10 and in the binary numeration system, the base is 2. The value e 2. 718 is the natural base. 2. A reference value. 3. A number that is multiplied by itself as many times as indicated by an exponent.