五年级下册数学课件-1-2235的倍数的特征共16张PPT-西师大版

1、第,1,单元第,2,课时,2,3,5,的倍数特征,西师大版五年级数学下册,复习引入,一,做,在,1,100,的自然数里，你能找出,9,的,做,所有倍数吗？最小的倍数是多少,9,的倍数,9,18,27,36,45,54,63,72,81,90,99,其中最小的倍数是,9,探究新知,1,2,的倍数有哪些,2,1=2,2,2=4,2,的倍数,有无数个,2,3=6,2,4=8,2,5=10,观察这些数，它们个位上,的数有什么特点,0,是,奇,数,还,是,偶,数,偶,数,个位上是,0,2,4,6,8,的数,都是,2,的倍数,它们是偶数,奇,数,个位是,1,3,5,7,9,的数,都不是,2,的倍,数，它们

2、是奇,数,在,百,数,表,中,找,出,5,的,倍,数,2,1,1,11,11,21,21,31,2,2,12,12,22,22,32,5,的倍数有什么特征,3,3,13,13,23,23,33,4,4,14,14,24,24,34,34,5,5,15,15,25,25,35,35,6,6,16,16,26,26,36,36,7,7,17,17,27,27,37,37,8,9,9,8,18,19,19,18,28,29,29,28,38,39,39,38,10,10,20,20,30,30,40,40,41,42,43,44,44,45,45,46,46,47,47,48,48,49,49,50

3、,50,54,55,55,56,56,57,57,58,58,59,59,60,60,51,52,53,54,64,65,65,66,66,67,67,68,68,69,69,70,70,61,62,63,64,74,75,75,76,76,77,77,78,78,79,79,80,80,71,72,73,74,84,85,85,86,86,87,87,88,88,89,89,90,90,81,82,83,84,91,92,93,94,94,95,95,96,96,97,97,98,98,99,99,100,100,个位上,是,0,或,5,的数,是,5,的,倍数,观察：这组数有什么特征呢,1,

4、2,3,4,5,6,7,8,9,10,20,30,40,50,60,70,11,12,13,14,15,16,17,18,19,21,22,23,24,25,26,27,28,29,个位上是,0,的数，既是,2,的倍数也,是,5,的倍数,31,32,33,34,35,36,37,38,39,41,42,43,44,45,46,47,48,49,51,52,53,54,55,56,57,58,59,61,62,63,64,65,66,67,68,69,71,72,73,74,75,76,77,78,79,81,82,83,84,85,86,87,88,89,80,90,91,92,93,94,9

5、5,96,97,98,99,100,3,找规律,将一些小圆片放在下图中,表示成一个一位数或两位数,十位,个位,填表，判断组成的数是不是,3,的倍数,圆片个数（个,3,4,5,6,摆成的数,是不是,3,的倍数,12,31,23,42,是,不是,不是,是,观察上表，你发现了什么规律,在百数表中找出,3,的倍数,1,2,3,4,5,6,7,8,9,10,20,30,40,50,60,70,80,90,11,12,13,14,15,16,17,18,19,21,22,23,24,25,26,27,28,29,31,32,33,34,35,36,37,38,39,41,42,43,44,45,46,47

6、,48,49,51,52,53,54,55,56,57,58,59,61,62,63,64,65,66,67,68,69,71,72,73,74,75,76,77,78,79,81,82,83,84,85,86,87,88,89,91,92,93,94,95,96,97,98,99,100,1,3,的倍数的末尾的数有规律吗,2,选取几个,3,的倍数，把各个数位,上的数字加起来，你有什么发现,3,试着总结,3,的倍数的特征,一个数，如果各数位上的,数字之和,是,3,的倍数，这个数就是,3,的倍数,一,试,试,巩固练习,把果实又快又准地装进袋子里,7,18,74,46,91,89,18,74,46,偶数,7,91,89,奇数,一筐苹果有若干个（个,数在,70,100,以内,2,个,2,个地数正好数完,5,个,5,个地数也正好数完。这,筐苹果可能有多少个,可能是,70,个，也可能是,80,个,还可能是,90,个或,100,个,把下面各数填在合适的圆圈里,20,42,15,36,75,23,126,60,90,126,42,36,75,42,15,36,75,90,60,126,20,90,60,15,2,的倍数,5,的倍数,3,的倍数,课堂小结,通过本节课学习,你有什么收获,2,个位