Sum the following series:
0.5 + 0.55 + 0.555.......... to n terms
Let = 0.5 + 0.55 + 0.555 +............ to n terms
          = 5[0.1 + 0.11 + 0.111 + ........... to n terms]
          =
          =
          =
          =
         Â
Find the least value of n for which the sum 1 + 3 + 32+ ...... to n terms is greater than 7000.
The ratio of the sum of first three terms is to that of first 6 terms of a G.P. is 125 : 152. Find the common ratio.
If S1, S2 and S3 be respectively the sums of n, 2n and 3n terms of a GP., prove that S1 (S3 – S2) = (S2 – S1)2
Let S be the sum, P the product and R the sum of the reciprocals of n terms in a G.P. Prove that