x = 1 + 3 + 5 + 7 + ..........+ 307
→ aflam cati termeni are suma, stiind ca ratia este 2
( 307 - 1 ) : 2 + 1 = 306 : 2 + 1 = 153 + 1 = 154 termeni are suma
→ aplic formula sumei lui Gauss
x = 154 × ( 1 + 307 ) / 2
x = 154 + 308 / 2
x = 154 × 154
x = 154²→ patrat perfect
