1+2+3+...+145=145x(145+1)/2=145x146/2=145x73=10585
Răspuns
1 + 2 + 3 + 4 + ...... + 145 = 10 585
= 145 × ( 1 + 145 ) : 2 =
= 145 × 146 : 2 =
= 145 × 73 =
= 10 585