# How are exponential functions related to geometric sequences?

Geometric sequences are formed by choosing a starting value and generating each subsequent value by multiplying the previous value by some constant called the geometric ratio. If a formula is provided, terms of the sequence are calculated by substituting $n = 0 , 1 , 2 , 3 , \ldots$ into the formula. Note how only whole numbers are used, because it doesn't make sense to have a "one and three-quarterth" term. With an exponential function, the inputs can be any real number from negative infinity to positive infinity.