二分之一加六分之一加十二分之一加二十分之一加三十分之一(要过程)
1/2+1/6+1/12+1/20+1/30
=1*3/(2*3)+1/6+1/12+1/20+1/30
=3/6+1/6+1/12+1/20+1/30
=4/6+1/12+1/20+1/30
=8/12+1/12+1/20+1/30
=9/12+1/20+1/30
=3/4+1/20+1/30
=15/20+1/20+1/30
=16/20+1/30
=4/5+1/30
=24/30+1/30
=25/30
=5/6
red
i
原式
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6
=1-1/6
=5/6