1.125+2.125+3.125+4.125……80.125=?
问题描述:
1.125+2.125+3.125+4.125……80.125=?
答
用1+80的和*80/2=3240,再用0.125*80+3240=3250
算式:(1+80)*80/2+0.125*80=3250