S = 10 + 13 + 16 + ......+ 157 =
→ stabilim cati termeni are suma , cu ratia 3 ( 13 - 10 = 3; 16 - 13 = 3 )
( 157 - 10 ) : 3 ( ratia) + 1 = 147 : 3 + 1 = 49 + 1 = 50 termeni are suma
→ aplic formula sumei lui Gauss: nr. termeni x suma dintre primul si ultimul termen supra 2
S = 50 x ( 10 + 157 ) / 2
S = 25 x 167
S = 4 175
