1 + 3 + 5 + 7 + ......+ 1 007 =
→ aflam cati termeni are suma; ratia = 2
( 1 007 - 1 ) : 2 + 1 = 1 006 : 2 + 1 = 503 + 1 = 504 termeni are suma
→ aplic formula sumei lui Gauss
= 504 × ( 1 + 1 007 ) / 2 = 504 × 1 008 / 2 = 504 × 504 = 504²→ patrat perfect
