请用简便方法计算这道数学题

题目应该是：(1-1/2²)(1-1/3²)(1-1/4²)……(1-1/11²)(1-1/12²)=？

解：
原式
=(1+1/2)(1-1/2)(1+1/3)(1-1/3)(1+1/4)(1-1/4)...(1+1/11)(1-1/11)(1+1/12)(1-1/12)
=[(1+1/2)(1+1/3)(1+1/4)...(1+1/11)(1+1/12)]*[(1-1/2)(1-1/3)(1-1/4)...(1-1/11)(1-1/12)]
=[3/2*4/3*5/4*...*12/11*13/12]*[1/2*2/3*3/4*...*10/11*11/12]
=[1/2*13]*[1*1/12]
=13/2*1/12
=13/24