Tính nhanh : A= 1/2002 + 2/2002 + 3/2002 +...+2000/2002 + 2001/2002

    `A= 1/2002 + 2/2002 + 3/2002 +...+2000/2002 + 2001/2002`

`= (1+2+3+...+2000+2001)/2022`

`Đặt:` `B=1+2+3+...+2000+2001`

Số số hạng:

    `(2001-1)/1 +1=2001(số)`

Tổng `B` là:

    `B=( (2001+1) xx 2001 )/2=2003001`

`Thay` `B` vào `A`, `ta` ` có:`

    `A=B/2022=2003001/2022=2001/2=1000,5`

` Vậy,` `A=1000,5`

`***` $2k10kaitokid$