[tex]\bf A = 9+99+999+........+{\underbrace{999......99}}_{\it2019\:cifre\:de 9}}[/tex]
[tex]\bf A = 10+100+1000+10000+.....+{\underbrace{1000.....00}}_{\it\:2019\:cifre\:de\:0}}-1\cdot2019[/tex]
[tex]\bf A = {\underbrace{111....11}}_{\it 2019\:cifre\:de\:1}}-2019[/tex]
[tex]\bf A = {\underbrace{111.....11}}09091}__{\it 2015\:cifre\:cifre de\:1}[/tex]
A = are doua cifre de 9, adica n = 2
Varianta c) in cazul tau
