56 + 57 + 58 + ........... + 189 + 190 = 16 605
→ stabilesc cati termeni are suma cu ratia = 1
190 - 56 + 1 = 135 termeni are suma
→ aplic formula sumei lui Gauss
= 135 × ( 56 + 190 ) : 2 =
= 135 × 246 : 2 =
= 135 × 123 =
= 16 605
