是
是的.
因为两个数字相乘满足交换律.如果已经判断出c能被b整除,则c一定能被(c/b)整除.因此,我们只要搜索到 b=c/b即可,也就是b^2=c
判断一个正整数N是否为质数的一个方法是只需判断2到小于等于根号N的质数是否能整除它即可？
比如说37是质数,因为 2, 3, 5 (5是小于等于根号37的质数)不能整除它
It is because any other composite number less than the
square root of N that devides N implies its prime
factor(s) must also devide it.
Besides this, any number that is greater than the square
root of N and devides N must have another factor that is
less than the square root of N accompanying and
therefore has been tested before.
参考资料：||
