197.    

The integers m and p are such that 2 < m < p and m is not a factor of p.  If r is the remainder when p is divided by m, is r > 1 ?

(1)  The greatest common factor of m and p is 2.

(2)  The least common multiple of m and p is 30

这题答案1可以推测出,因为两数最大公约数是2,那可以排除相邻的可能,那余数肯定大于1.

答案2,我只知道把30分解成质因子:2*3*5,则15,10相除余5,10,6相除余4,.....都大于1呀,

但是正确答案是A,请问大家,我的思路错在哪儿呀?

非常感谢.

还有一道关于最大公约,最小公倍数的题一并来请教了.

88.     8066-!-item-!-187;#058&005745

What is the greatest common divisor of positive integers m and n ?

(1) m is a prime number.

(2) 2n = 7m

根据1,不知N,所以不确定;2, M,N只知道它们是2/7倍数关系,也不确定;1+2,M只可能等于2,所以可以确定了.

请问这样的思路对吗?

很感谢