18+19+20+21.79+80+81+82=?
18+19+20+21.79+80+81+82=?
1000-81-82-84-85-19-18-17-16-15-83=?用简便方法计算
15+16+17+18+19+20+.+81=多少?
1000-81-19-82-18-83-17-84-16-85-15-84-16-83-17-82-18-81-19
80,81,82,83
1000-81-19-82-18-83-17-84-16-85-14-87-16-88-12-89-11=
77+78+79+80+81+82+83=
79+80+81+82……+100= 简便计算
80+81+82+83+84
数学运算1/(80*81) + 1/(82*82) + .+1/(99*100)=?
数学运算1/(80*81) + 1/(81*82) + .+1/(99*100)=?
78+79+80+81+82=80×5.______.