公因数、公倍数(精品)

,找最小公倍数,返回,找最小公倍数,课前导入,探究新知,课堂小结,课后作业,分数的意义,课堂练习,5,课前导入,同学们，我们在前面学习了最大公因数的知识，今天我们来一起学习最小公倍数的知识。,4,，,12,9,，,18,1,，,2,3,，,6,12,的因数,18,的因数,12,和,18,的公因数,12,和,18,的公因数有：,。,1,，,2,，,3,，,6,12,和,18,的最大公因数有：,。,6,八五折,探究新知,在下表中用“”标出,4,的倍数，用“”标出,6,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,哪些数上既标有“”又标有“”？这些数有什么特点？,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,两种标记都有的数是,12,24,36,48,。,12,24,36,48,这些,数,既,是,4,的倍数也是,6,的倍数,。,4,和,6,的相同的倍数是它们的,公倍数,，其中最小的一个是它们的,最小公倍数,。,4,和,6,的公倍数有：,。,12,、,24,、,36,、,48,、,4,和,6,的最小公倍数是：,。,12,认一认，填一填。,淘,气用,下面的方法表,示公倍数，,你能看懂吗？,4,，,8,，,16,，,20,，,6,，,18,，,30,，,12,，,24,4,的倍数,6,的倍数,4,和,6,的公倍数,课堂练习,1.,在,下表中用“”标出,3,的倍数，用“”标出,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,哪些数上既标有“”又标有“”？,两种标记都有的数是,15,，,30,，,45,。,2.,填,一填。,1,2,3,4,5,6,7,8,9,10,8,8,16,6,6,12,24,32,40,48,56,64,72,80,18,24,30,36,42,48,54,60,50,以内,6,和,8,的公倍数有,，,最小公倍数是,。,24,，,48,24,3.,想,一想，填一填，,6,和,9,的最小公倍数是多少？,6,，,12,，,24,，,30,，,42,，,48,9,，,27,，,45,18,，,36,50,以内,6,的倍数,50,以内,9,的倍数,50,以内,6,和,9,的公倍数,4.,求,下面各组数的最小公倍数。,3,和,6,8,和,10,2,和,7,6,和,10,（,6,）,（,40,）,（,14,）,（,30,）,这节课你们都学会了哪些知识？,找两个数的公倍数，可以先把两个数倍数分别写一些出来，再看其中相同的部分。,课堂小结,两个数的公倍数中最小的一个是最小公倍数。,1.,从教材课后习题中选取；,2.,从课时练中选取。,课后作业,