数学ps不会做

HoneyStella

An integer greater than 1 that is not prime is called composite.  If the two-digit integer n is greater than 20, is n composite?
(1)     The tens digit of n is a factor of the units digit of n.
(2)     The tens digit of n is 2.

	Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
	Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
	BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
	EACH statement ALONE is sufficient.
	Statements (1) and (2) TOGETHER are NOT sufficient.

wolfheulen

答案为A
第一个条件： 设十位数为x，则个位数为mx, m为正整数。n = x + mx. n is composite.
第二个条件：23为质数，24为合数。十位数=2不说明问题

gaor

读懂题应该就能做了
The tens digit is the tens place of the number; it is the second digit on the right of the number (十位数)
The units digit is the one's place of the number; it is the first digit on the right of the number(个位数)
还有百位数千位数以此类推 'the hundreds digit' ..