1 + 5 + 9 + ...... + 301 = 11 476
→ stabilesc cati termeni are suma cu ratia = 4
( 301 - 1 ) : 4 + 1 = 300: 4 + 1 = 75 + 1 = 76
→ aplic formula sumei lui Gauss
= 76 × ( 1 + 301 ) : 2 =
= 38 × 302 =
= 11 476
________________________
2 + 5 + 8 + ........ + 599 =60 100
( 599 - 2 ) : 3 + 1 = 597 : 3 + 1 = 199 + 1 = 200 termeni
= 200 × ( 2 + 599 ) : 2 =
= 100 × 601 =
= 60 100
