
The term of the Arithmetic Progression (A.P) is given by .

Arithmetic mean between and is given by .

If denotes the sum up to terms of A.P. then where stands for last term,

The sum of A.M’s between and is .

The term of the geometric progression is .

Geometric mean between and is .

If denotes the sum up to terms of G.P is , where

The sum of infinite geometric series is

The term of the harmonic progression is .

Harmonic mean between and is .

and ; where are usual notations.