0,1=1/10
0,1^2=(1/10)^2
0,1^3=(1/10)^3
...........................
0,1^50=1/10^50
Observi ca termenii sunt in progresie geometrica de ratie q=1/10
Suma numerelor= suma termenilor unei Pg cu n= 50 termeni
S50=1/10*[1-(1/10)^50]/(1-1/10)=[1-(1/10)^50]/9
0,99...9(de 50 ori)/9=0,11...1 <1/4
