分数和小数的互化

,成功属于每天都努力学习的人！,推山小学刘征军,第2课时分数和小数的互化（2）,温故知新,把下面小数化成分数。0.625=,0.81=,如果要把分数化成小数，该怎么做呢？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,2,把化成小数（除不尽的保留两位小数）。,探究新知,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,（1）、写成小数分别是多少？,分母是10，100，1000，的分数化成小数，可以直接去掉分母，看1后面有几个0，就在分子中最后一位起向左数几位，点上小数点。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,（2）、写成小数分别是多少？,利用分数与除法的关系，用分子除以分母得出小数。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,分母不是10，100，1000，的分数化成小数，用分子除以分母，如果分子除以分母除不尽，要根据需要按“四舍五入”法保留几位小数。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,做一做,这6个数中，有分数、有小数，要比较这些数的大小，该怎么办？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,0.25,0.7,若是把小数转化成分数怎么做呢？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,达标检测,1.填空,把化成小数时，整数部分不变，直接去掉分母，看分母1后面有几个0，就在分子中从（）起，向（）数出（）位，点上（）结果是（）。,最后一位,左,3,小数点,1.007,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,2.把下面的分数化成小数（不能化成有限小数的保留两位小数）。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,方法一：0.960=54（个）5450,李阿姨和王叔叔谁打字快些？,我平均每秒打0.9