初一数学题〔1减2的平方分之1〕〔1减3的平方分之1〕〔1减4的平方分之1〕···〔1减10的平方分之1〕=?

(1-2^2)(1-3^2)(1-4^2)...(1-10^2)
=(1-1/2)(1+1/2)(1-1/3)(1+1/3)(1-1/4)(1+1/4)...(1-1/10)(1+1/10)
=(1/2)*(3/2)*(2/3)*(3/4)*(3/4)*(4/5)*...*(9/10)*(11/10)
=91/2)*(11/10)
=11/20.