新人教版五年级数学下册2、5、3的倍数的特征(第1、2课时).ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,1,、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？,复习：,2,、在,6,、,10,、,12,、,15,、,18,、,20,这几个数中，哪些数是,2,的倍数？哪些数是,5,的倍数？,40,的因数有,2,，,5,，,8,，,10,，,40,。,5,的倍数有,5,，,10,，,25,，,40,。,2,的倍数有,6,，,10,，,12,，,18,，,20,。,5,的倍数有,10,，,15,，,20,。,1,2,、,5,的倍数的特征,第一课时,2,座位号是多少的同学应该从双号入口进。,座位号是,2,，,4,，,6,，,8,，,2,的倍数的特征,3,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,2,的倍数,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,4,2,=1,2,4,=2,2,6,=3,2,8,=4,2,10,=5,2,12,=6,2,这些数都是,2,的倍数。你发现,2,的倍数有什么特征？,个位上是,0,，,2,4,，,6,，,8,的数都是,2,的倍数。,5,自然数中，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,。,1,2,3,4,5,6,7,2,4,6,8,10,12,14,2,2,的倍数的数,6,自然数中，是,2,的倍数的数叫做偶数（,0,也是偶数），不是,2,的倍数的数叫做奇数。,自然数,奇数,偶数,不能被,2,整除的数，个位上是,1,，,3,，,5,，,7,，,9,。,能被,2,整除的数，个位上是,0,，,2,，,4,，,6,，,8,。,7,最小的偶数是几？有没有最大的偶数？,最小的奇数是几？有没有最大的奇数？,最小的偶数是,0,，没有最大的偶数。,最小的奇数是,1,，没有最大的奇数。,考 考 你,8,下列数中，哪些是奇数，哪些是偶数？,33 98 355 988 0 123,3678 8089 1000 655 5656 881,奇数有：,33,，,355,，,123,，,8089,，,655,，,881,。,偶数有：,98,，,988,，,0,，,3678,，,1000,，,5656,。,9,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,5,的倍数,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,5,的倍数的特征,10,5,的倍数有,1,5,=5,2,5,=10,3,5,=15,4,5,=20,5,5,=25,6,5,=30,个位上是,5,或,0,的数,是,5,的倍数。,11,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 67 90 99 15,60 75 106 130 521 280,2,的倍数：,24,，,90,，,60,，,106,，,130,，,280,。,5,的倍数：,35,，,90,，,15,，,60,，,75,，,130,，,280,，,既是,2,的倍数也是,5,的倍数：,90,，,60,，,130,，,280,。,做完这道题，你有什么发现？,12,既是,2,的倍数也是,5,的倍数：,90,，,60,，,130,，,280,。,个位上是,0,的数，既是,2,的倍数也是,5,的倍数。,13,思考：,奇数,+,偶数,=,（）；,奇数,+,奇数,=,（）；,偶数,+,偶数,=,（）。,奇 数,偶 数,偶 数,14,食品店运来,85,个面包，如果每,2,个装一袋，能正好装完吗？如果每,5,个面包装一袋，能正好装完吗？为什么？,15,数学游戏,16,3,的倍数的特征,第,2,课时,17,在左表中找出,3,的倍数，并做上记号。,3,的倍数的特征,18,观察,3,的倍数，你发现了什么？与同学说一说。,19,3,的倍数的数,1,2,3,4,5,6,7,3,3,6,9,12,15,18,21,把,3,的倍数的各位上的数相加，看看你有什么发现,?,20,3,的倍数的数,1,2,3,4,5,6,7,3,3,6,9,12,15,18,21,1+2=3,1+5=6,1+8=9,2+1=3,12,15,18,21,个位上的数不是,3,的倍数，但各位数的和：,3,，,6,，,9,是,3,的倍数。,21,3,的倍数的数,一个数各位上的数的和是,3,的倍数，这个数就是,3,的倍数。,3,13=39,3,23=69,3+9=12,6+9=15,22,23,1,、下列数中,3,的倍数,有,_,。,14 35 45 100 332 876 74 88,45,，,876,一个数各位上的数的和是,3,的倍数，这个数就是,3,的倍数。,24,2,、既是,2,和,5,的倍数，又是,3,的倍数的最小三位数是多少？,最小三位数是：,120,个位上是,0,的数，既是,2,的倍数也是,5,的倍数。,三位数应该是,几百几十,要求最小三位数,三位数应该是,一百几十,各位上的数的和是,3,的倍数，这个数就是,3,的倍数。,25,选出两个数字组成一个两位数，分别满足下面的条件。,（,1,）是,3,的倍数。,（,2,）同时是,2,和,3,的倍数。,（,3,）同时是,3,和,5,的倍数。,（,4,）同时是,2,、,3,、,5,的倍数。,26,