2的倍数的特征.ppt

1、,第 1 课时 2、5的倍数的特征,R五年级下册,2. 2、5、3的倍数的特征,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,在 2、3、5、8、10、12、25、40 这几个数中，40 的因数有几个？5 的倍数有几个？,40的因数有：2，5，8，10，40,5的倍数有：5，10，25，40,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元

2、成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,你能快速判断下面这几个数，哪几个是 2 的倍数？哪几个是 5 的倍数？,3245 2963 8037 7231 12035 4570,（1）哪些是5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,仔细观察，请你说一说这些数字有哪些特点？,个位上是_或_的数都是5的倍数,0,5,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,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,28，45，53，80，89，75，34，95 200，305,在下面的数中圈出5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,（2）哪些是2的倍数？把它们圈起来。,个位上是0,2,_的数都是2的倍数,4,6,8,状元成才路,状元成才路,状元成才路,状元

4、成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,下面这些数是2的倍数吗？,175,2243,700,3375,55578,798,667,336,4006,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,整数中，是2的倍数的数叫做偶数（0也是偶数），不是2的倍数的数叫做奇（j）数。,偶数：0,2,4,6

5、,8,10,12,奇数：1,3,5,7,9,11,13,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,19 357 642 300 567 2221 7009,100 1104 790 998 456 33332,奇 数,偶 数,19,357,567,2221,7009,642,300,100,1104,790,998,456,33332,下面哪些数是2的倍数？哪些数是5的倍数？哪些数既是2的倍数，也是5的倍数？,24 35

6、67 90 99 15 106 60 75 130 521 280 6018 8100,2 的倍数有：24，90，106，60，130，280，6018，8100。,5 的倍数有：35，90 ，15，60 , 75，130，280，8100。,90，60，130，280，8100既是 2 的倍数又是 5 的倍数。,24 35 67 90 99 15 106 60 75 130 521 280 6018 8100,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元

7、成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,个位上是0的数既是2的倍数又是5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,归纳小结,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

8、的倍数,个位上是 0 的数既是 2 的倍数又是 5 的倍数,偶数：个位上是 0,2,4,6,8 的数,奇数：个位上是 1,3,5,7,9 的数,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,1、一个自然数不是奇数就是偶数。,2、偶数都比奇数大。,3、个位上是 2,4,6,8,0 的自然数都是偶数。,4、一个数是 2 的倍数，那它一定是偶数。,5、能被 2,5 整除的数个位上的数字一定是 0。,一、下面的说法对吗？说出理由。,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,二、填一填。,1.个位上是（ ）的数能被 2 整除，能被 2 整除的数叫做（ ）不能被 2 整除的数叫做（ ）。 2. 20 以内的所有奇数的和是（ ）。 3.三个连续奇数，中间一个是 a ，其它两个数分别是（ ）和（ ）。 4. 3 个连续的偶数的和是 60 ，这三个数分别是（ ）（ ）（ ）。,0,2,4,6,8,偶数,奇数,100,a-2,a+2,18,20,22,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,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,三、用 0、2、5 这三个数字组成一个三位数，,使它有因数 2 ，这样的数有哪些？,520 502 250,如果是 5 的倍数，这样的数又有哪些？,520 205 250,既是 2 的倍数，又是 5 的倍数有那些？,520 250,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,奇数与偶数的和是奇数还是偶数？奇数与奇数的和是奇数还是偶数，偶数与偶数的和呢？,奇数偶数（ ） 奇数奇数（ ） 偶数偶数（ ）,奇数,偶数,偶数,1. 课本P11-12，第6题、第7题、第12题； 2. 完成练习册本课