`(1/4-1).(1/9-1).(1/16-1)...(1/900-1) . 4/3`
`=(-3)/4 . (-8)/9 . (-15)/16 ... (-899)/900 . 4/3`
`=(-1.3)/(2.2) - (-2.4)/(3.3) . (-3.5)/(4.4) ... (-29.31)/(30.30) . 4/3`
`=((-1).(-2).(-3)...(-29))/(2.3.4...30) . (3.4.5..31)/(2.3.4...30) . 4/3`
`=-((1.2.3..29)/(2.3.4...30)) . (3.4.5...31)/(2.3.4...30) . 4/3`
`=-1/30 . 31/2 . 4/3`
`=-31/60 . 4/3`
`=-31/45`