2, 1, \(\frac{1}{2}\), \(\frac{1}{4}\)..... There are 4 terms in the series Therefore the next number will be the 5th term Tn = ar\(^{n − 1}\) (formular for geometric series) a = first term = 2 r = common rate = \(\frac{\text{next term}}{\text{previous term}}\) = \(\frac{1}{2}\) n = number of terms T5 = 5th term = ? T5 = ar\(^{5 - 1}\) = ar\(^4\) = 2 × (ar\(^{n − 1}\))4 = 2 × \(\frac{1}{16}\) = \(\frac{1}{8}\)