9分之8乘9分之8除9分之8乘9分之8 =(8/9)÷(8/9)×(8/9)×(8/9)=1×(8/9)×(8/9)=64/81
（8/9)×（8/9)÷（8/9）×（8/9）=（8/9)×（8/9)×（9/8）×（8/9）=（8/9)×1×（8/9）= 64/81
