`S = 10. (1/(2.12) + 1/(12.22) + 1/(22.32) + ...+1/(2002.2012) )`
`S = 10/(2.12) + 10/(12.22) + 10/(22.32) + ...+10/(2002.2012)`
`S = 1/2 - 1/12 + 1/12-1/22+1/22-1/32+.....+1/2002-1/2012`
`S = 1/2 - 1/2012`
`S = 1006/2012 - 1/2012`
`S = 1005/2012`
(Chúc bạn học tốt)