1/4×5+1/5×6+1/6×7+1/7×8=
1/4×5+1/5×6+1/6×7+1/7×8=
1 2 3 4 5 6 7 8=1
1、1/4*5+1/5*6+1/6*7+1/6*8+.+1/99*100
(7\8-1\5)x5\6=
1-1/3-1/4=?,1/7×7÷1/7×7=?,1-5÷9=?,3/4×5/6×8/15=?
计算:1/3*4+1/4*5+1/5*6+1/6*7+1/7*8+1/8*9
5-1-1-7-2-1-8-6=?
1+2+3+4+5+6+7+8=
1+2+3+4+5+6+7+8+9=?
1/3*4+1/4*5+1/5*6+1/6*7+.1/99*100=?
1/9+1/5+3/5+4/9+2/3+7/8+1/6+5/7+3/7+5/8+3/5+1/8+2/9=?
数列计算 1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9=?