6.8×0.5的简便运算6.8×0.5=3.4x2x0.5=3.4x1=3.4
6.8x0.5=6.8x½=3.4
6.8x0.5=6.8x1/2=3.4
=（3.4*2）*0.5=3.4*（2*0.5）=3.4*1=3.4
