3的倍数的特征.ppt

1、,第2课时3的倍数的特征,五年级下册,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,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,117,是2的倍数吗？,是5的倍数吗？,个位上是0、2、4、6、8的数是2的倍数,个位上是0或5的数是5的倍数,2、5的倍数为什么只与个位有关呢？,状元成才路,状元成才路,状元成才路,状元成

2、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,117,100250,1025,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,117,100520,1052,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

3、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,几个10,个位,十位,百位,千位,几个100,几个1000,2、5的倍数,6,5,9,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,3的倍数特征,会不会只与个位有关呢？,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

4、,状元成才路,状元成才路,（1）上表中哪些是3的倍数？把它们圈起来。,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）横着看，圈起来的前10个数，个位分别是哪些数字。,3,6,9,2,5,8,1,4,7,0,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,（

5、2）判断一个数是不是3的倍数，只看个位行吗？,3,6,9,2,5,8,1,4,7,0,3的倍数个位上可以是任意数。,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,（3）斜着看，你发现了什么？,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,斜着看，3的倍数各位上

6、的数的和都是3的倍数。,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,任意找几个3的倍数，把各位上的数相加，看看你有什么发现？,42,4+2=6，6是3的倍数,78,7+8=15，15是3的倍数,一个数各位上的数的和是3的倍数，这个数就是3的倍数。,归纳小结,2的倍数：个位是0、2、4、6、8,5的倍数：个位是0、5,3的倍数：各位上数字之和是3的倍数,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

7、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,117,1003331,10331,1+1+79,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,127,1003331,20362,1+2+710,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

8、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,下面用数字卡片摆出的数字中哪些是3的倍数？在每个数后面增加一张卡片，使这个三位数成为3的倍数。,2,4,5,8,2+4=624是3的倍数,0,3,6,9,5+8=1358不是3的倍数,2,5,8,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,4,7,9,6,4+7=1147不是3的倍数,1,4,7,9+6=1596是3的倍数,0,3,6,9,智慧屋,状

9、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,1.圈出3的倍数。,927536206653051779999991114916559886551312227203,这种方法叫“弃3”法，就是先把3的倍数划去，剩下的数再相加判断。,2.在里填一个数字，使每个数都是3的倍数。,7424465121,2,5,8,0,3,6,9,1,4,7,1,4,7,2,5,8,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,

10、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,3.下面的判断正确吗？小组间相互讨论一下。,（1）个位上是3、6、9的数，都是3的倍数。,（2）奇数都不是3的倍数。,（3）是9的倍数的数，一定是3的倍数。,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,4.从下面4张数字卡片中取出两张组成两位数，要求分别满足下面的条件：,4,3,0,5,（1）是3的倍数,（2）同时是2和3的倍数,30,45,54,30,54,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