37 + 43 + 49 + ...... + 115 =
→ aflam cati termeni are suma
43 - 37 = 6 → ratia progresiei aritmetice
( 115 - 37 ) : 6 + 1 = 78 : 6 + 1 = 13 + 1 = 14 termeni are suma
→ aplic formula sumei lui Gauss:
37 + 43 + 49 + ....... + 115 = 1 064
= 14 x ( 37 + 115 ) / 2 =
= 7 x 152 =
= 1064
