Question

Calculeaza prin meteda guess 2+4+6+...+140=?

Answer 1

2+4+6+...+140 = 2(1+2+...+70) = 2 * ( 70 * 71 ) : 2 = 70*71 = 4970

Answer 2

2+4+6+...+140=?
140:2=70
70*(2+140):2
70*142:2
9940:2
4970
Sper ca te-am ajutat!
Coronita??