√20.17=√（2017x0.01）=√2017×0.1=44.91×0.1=4.491被开方数小数点向左(向右)每移动2位，开方结果的小数点要向左(向右)移动1位
√20.17=√（2017x0.01）=0.1√2017=0.1x44.91=4.491
