In a geometric progression, every adjacent numbers of the progression have a common ratio.
For eg- 2,4,8,16,32,64
42=84=168=3216=6432=2
The first term is denoted as 'a' and the common ratio is denoted by 'r' (which is 2 in the above example).
nth term of a GP=a(r)n−1
(where n is the number of terms)