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,*,质数和合数,填写,1,20,各数的因数，看看它们的因数的个数有什么规律。,1,的因数有,11,的因数有,2,的因数有,12,的因数有,3,的因数有,13,的因数有,4,的因数有,14,的因数有,5,的因数有,15,的因数有,6,的因数有,16,的因数有,7,的因数有,17,的因数有,8,的因数有,18,的因数有,9,的因数有,19,的因数有,10,的因数有,20,的因数有,1,1,，,2,1,，,3,1,，,2,，,4,1,，,5,1,，,2,，,3,，,6,1,，,7,1,，,2,，,4,，,8,1,，,3,，,9,1,，,2,，,5,，,10,1,，,11,1,，,2,，,3,，,4,，,6,，,12,1,，,13,1,，,2,，,7,，,14,1,，,3,，,5,，,15,1,，,2,，,4,，,8,，,16,1,，,17,1,，,2,，,3,，,6,，,9,，,18,1,，,19,1,，,2,，,4,，,5,，,10,，,20,只有一个因数,只有,1,和它本身两个因数,有两个以上的因数,一个数，如果只有,1,和她本身两个因数，这样的数叫做,质数（或素数）,。,1,2,，,3,，,5,，,7,，,11,，,13,，,17,，,19,4,，,6,，,8,，,9,，,10,，,12,，,14,，,15,，,16,，,18,，,20,2,，,3,，,5,，,7,，,11,，,13,，,17,，,19,一个数，如果除了,1,和它本身还有别的因数，这样的数叫做,合数。,1,不是质数，也不是合数。,只有一个因数,只有,1,和它本身两个因数,有两个以上的因数,1,2,，,3,，,5,，,7,，,11,，,13,，,17,，,19,4,，,6,，,8,，,9,，,10,，,12,，,14,，,15,，,16,，,18,，,20,4,，,6,，,8,，,9,，,10,，,12,，,14,，,15,，,16,，,18,，,20,判断下列各数中哪些是质数，哪些是合数。,17 22 29 35 37 87 93 96,质数：,17,，,29,，,37,。,合数：,22,，,35,，,87,，,93,，,96,。,找出,100,以内的质数，做一个质数表。,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,把,2,的倍数（,2,除外）先划去,找出,100,以内的质数，做一个质数表。,2,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95,97,99,把,5,的倍数（,5,除外）先划去,找出,100,以内的质数，做一个质数表。,2,3,5,7,9,11,13,17,19,21,23,27,29,31,33,37,39,41,43,47,49,51,53,57,59,61,63,67,69,71,73,77,79,81,83,87,89,91,93,97,99,把,3,的倍数（,3,除外）先划去,找出,100,以内的质数，做一个质数表。,2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,49,53,59,61,67,71,73,77,79,83,89,91,97,把,7,的倍数（,7,除外）先划去,100,以内的质数。,2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,下面各数中哪些是质数？哪些是合数？分别填入指定的圈里。,27 37 41 58 61 73 83 95,11 14 33 47 57 62 87 99,质数,合数,37,，,41,，,61,，,73,，,83,，,11,，,47,。,27,，,58,，,95,，,14,，,33,，,57,，,62,，,87,，,99,。,下面的说法正确吗？说说你的理由。,（,1,）所有的奇数都是质数。,（,2,）所有的偶数都是合数。,（,3,）在,1,，,2,，,3,，,4,，,5,，,中，除了质数以 外都是合数。,（,4,）两个质数的和是偶数。,