Question

1-2分之3+ 6分之5-12分之7+ .-90分之19 +110分之21=( ) 怎么算?

Answer 1

1-2分之3+ 6分之5-12分之7+ .-90分之19 +110分之21

=1-(1+1/2)+(1/2+1/3)-(1/3+1/4)+...-(1/9+1/10)+(1/10+1/11)

=1/11