Question

二分之一减二乘三分之一减三乘四分之一减四乘五分之一减五乘六分之一

Answer 1

1/2-1/(2*3)-1/(3*4)-1/(4*5)-1/(5*6)

=1/2-(1/2-1/3)-(1/3-1/4)-(1/4-1/5)-(1/5-1/6)

=1/2-1/2+1/3-1/3+1/4-1/4+1/5-1/5+1/6

=1/6