Question

Calculate the sum of the series

5 + 55 + 555 + ……..+ n

Answer 1

may b 61725
not sure it can b wrong.....

Answer 2

S=5+55+555+.........upto n terms. S=5(1+11+111+............upto nterms)
S=5/9(9+99+999+........n)
S=5/9(10-1+100-1+1000-1+....)
S=5/9(10+100+1000......upto n terms-n)
S=5/9[10(10powern-1)/9 -n]