Question

Find the sum of h terms of the series 5+55+555+.....​

Answer 1

Answer:

Sum = 5 + 55 + 555 + …. n terms.

= 5/9[9 + 99 + 999 + …. n terms]

= 5/9[(10 – 1) + (100 – 1) + (1000 – 1) + … n terms]

= 5/9[10 + 100 + 1000 ….. – (1 + 1 + … 1)]

= 5/9[10(10n – 1)/(10 – 1) + (1 + 1 + … n times))

= 50/81(10n – 1) – 5n/9