This is not a G.P., however we can relate it to a G.P. by writing the terms as $S_n$ = 8 +88 + 888 + 8888 + ...... to n terms Now, $S_n$ = $\frac{8}{9}$ [9 + 99 + 999 ...... to n terms] = $\frac{8}{9}$ [(10 - 1) + (100 - 1) + (1000 - 1) + ... to n terms] = $\frac{8}{9}$ [(10 + 100 + 1000 + ... to n terms) - (1 + 1 + ... to n temrs)] = $\frac{8}{9}$ [(10 + $10^2+10^3$ + ... to n terms) - (1 + 1 + 1 + ... to n terms)] = $\frac{8}{9}\left[\frac{10(10^n-1)}{9} - n\right]$ Since $S_n$ = $\frac{a(r^n-1)}{r-1}$ , if |r| > 1.