Răspuns :

1,2,3,4,5,6,7,8,9.
9+1=10
10,11,12...99
99+10=109
100,101...426
426+100=526 de cifre

1........9sunt9nr.x1cifra=9cifre
10.....99 sunt 90nr.x2=180cifre
100......426 sunt 327x3=981cifre
total:1170