简便算法3000-2-4-6-...-78-80
问题描述：
简便算法3000-2-4-6-...-78-80
答
=3000-(2+4+6+...80)=3000-[(2+80)*40]/2=3000-1640=1360
简便算法3000-2-4-6-...-78-80
=3000-(2+4+6+...80)=3000-[(2+80)*40]/2=3000-1640=1360