Sửa đề bài:
`( 1 - 1/2 ) × ( 1 - 1/3 ) × (1 - 1/4) × ( 1 - 1/5 ) × ...... × ( 1 - 1/50)`
`( 1 - 1/2 ) × ( 1 - 1/3 ) × (1 - 1/4) × ( 1 - 1/5 ) × ...... × ( 1 - 1/50)`
` = 1/2 × 2/3 × 3/4 × 4/5 × ... × 49/50`
` = (1×2×3×4×...×49)/(2×3×4×5×...×50)`
` = 1/(50)`