(1-2012/1)(1-2011/1)(1-2010/1) ...(1-3/1)(1-2/1)

(1-2012/1)(1-2011/1)(1-2010/1) ...(1-3/1)(1-2/1)
(1-2012/1)(1-2011/1)(1-2010/1) ...(1-3/1)(1-2/1)

(1-2012/1)(1-2011/1)(1-2010/1) ...(1-3/1)(1-2/1)
(1-1/2012)(1-1/2011)(1-1/2010)...(1-1/3)(1-1/2)
=(2011/2012)(2010/2011)(2009/2010)...(2/3)(1/2)
=(2011×2010×2009×...×2×1)/(2012×2011×2010×...×3×2)
=1/2012
顺便说一句,你分子分母写反了,水平书写分数的时候,分子写在“/”左边,分母写在“/”右边.