A series is in Arithmetic Progression (A.P.), if it has the following form:
a, a+d, a+2d, a+3d, ....
where a=First term and d=Common difference.
Some useful derivations from A.P. Series:
a, a+d, a+2d, a+3d, ....
where a=First term and d=Common difference.
Some useful derivations from A.P. Series:

