Question

40+41+42+......+100=? metoda lui Gauss

Answer 1

40 + 41 + 42 + ..... + 100 = 4 270

→ stabilesc cati termeni are suma cu ratia = 1

100 - 40 + 1 = 61 termeni are suma

= 61 × ( 40 + 100 ) : 2 =

= 61 × 140 : 2 =

= 61 × 70 =

= 4 270

Answer 2

1+2+3+...+100=(100×101)/2=50×101=5050
1+2+3+...+39=(39×40)/2=39×20=780
5050-780=4270