(1+1/2)*(1-1/2)*(1+1/3)*(1-1/3)*······*(1+1/50)*(1-1/50)

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(1+1/2)*(1-1/2)*(1+1/3)*(1-1/3)*······*(1+1/50)*(1-1/50)
(1+1/2)*(1-1/2)*(1+1/3)*(1-1/3)*······*(1+1/50)*(1-1/50)

(1+1/2)*(1-1/2)*(1+1/3)*(1-1/3)*······*(1+1/50)*(1-1/50)
用平方差
原式=(1-1/2)(1+1/2)(1-1/3)(1+1/3)……(1-1/50)(1+1/50)
=(1/2)(3/2)(2/3)(4/3)……(49/50)(51/50)
中间约分
=(1/2)(51/50)
=100分之51

原式= 3/2 * 1/2 * 4/3 * 2*3 ......50/49* 48/49 * 51/50 * 49/50
= 1/2 * 51/50
= 51/100