Question

一减二分之一减六分之一减十二分之一减二十分之一减三十分之一等于多少?请附竖式

Answer 1

1-1/2-1/6-1/12-1/20-1/30
=1-(1/2+1/6+1/12+1/20+1/30)
=1-(1/1×2+1/2×3+……+1/5×6)
=1-(1-1/2+1/2-1/3+1/3-1/4+……+1/5-1/6)
=1-(1-1/6)
=5/6