1、2、5倍数的特征,苏教版小学数学五年级(下册),主讲：,学习内容,学习内容,引入新知,认识了因数和倍数。,学会找一个数的因数和倍数的方法。,已学：,问题：,2的倍数有什么特征？,5的倍数有什么特征？,什么是奇数？什么是偶数？,探 究 新 知,1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64
2、,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,15,5的倍数有什么特征？,5的倍数个位上是5或0。,探 究 新 知,1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56
3、,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,15,一个数不是5的倍数，它的个位上不是5，也不是0。,探 究 新 知,1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,4
4、8,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,15,在你的自主学习任务单上，任意写一个个位是5或0的三位数，验证它是5的倍数吗？,245,670,2455=49,6705=134,探 究 新 知,1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,17,18,19,20,21,22,23,24,25,26,
5、27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,15,2的倍数个位上是2、4、6、8或0。,探 究 新 知,1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,17,18,19,20
6、,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,15,一个数不是2的倍数，它的个位上不是2、4、6、8、或0。,探 究 新 知,1,2,3,4,5,6,7,8,9,
7、10,11,12,13,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,15,在你的自主学习任务单上，任意写一个一定是2的倍数的三
8、位数。,探 究 新 知,1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100
9、,15,既是2的倍数又是5的倍数有什么特征？,个位上是0的数，既是5的倍数，又是2的倍数。,探 究 新 知,是2的倍数的数叫做偶数，不是2的倍数的数是奇数。,12是2的倍数，12是偶数。,201不是2的倍数，201是奇数。,在你的自主学习任务单上分别写一个偶数，一个奇数，并上传给老师。,双数,单数,巩固练习,5的倍数：,2的倍数：,既是5的倍数，又是2的倍数：,25，60，90,12，48，60，72，90,60，90,巩固练习,2.你们班的人数是奇数还是偶数？你家的门牌号呢？你还能举例说说生活中的奇数和偶数吗？,五2班人数58人。,从连云港到西安的火车是1150次列车。,我们家的门牌号是11
10、01。,我平常坐3路车上学。,58是偶数,1101是奇数,3是奇数,1150是偶数,巩固练习,5.下面的数，哪些是偶数？哪些是奇数？,58,74,89,120,231,155,偶数：,奇数：,58，74，120，600,89，231，155,600,巩固练习,6.选出两张数字卡片，按要求组成一个两位数。,0,（1）组成的数是偶数。,（2）组成的数是5的倍数。,（3）组成的数既是2的倍数，又是5的倍数。,50，60，70，56，76,50，60，70，65，75，,50，60，70,5,6,7,巩固练习,7.把下表中4的倍数涂色，看一看，4的倍数都是2的倍数吗？,4的倍数一定是2的倍数，2的倍数不一定是4的倍数。,回顾反思,今天学的知识能解决课前提出的问题吗？,1. 2的倍数有什么特征?,2. 5的倍数又有什么特征?,3. 什么是奇数？什么是偶数?,把你的答案写在自主学习单上，并上传给老师。,回顾反思,2、5的倍数为什么只看个位就可以判断？,学习检测,再 见 ！,
