[求助]天山 4-32

guafafd

Q32.

If n is an integer between 10 and 99, is n＜80?

(1) the sum of the two digits of n is a prime number.

(2) each of the two digits of n is a prime number.

The answer is B but my answer is E

(1) (1+8=prime) 81＞80 18＜80 , so wrong

(2) 79＜80 97＞80, so wrong

(1)+(2) 29＜80 92＞80 ,so the answer is E

himba

up

mikejia

sorry

from 81 to 99

81 82 83 84 ....89

90 91 ... 99

8 and 9 aren't prime number

[此贴子已经被作者于2004-12-21 13:45:43编辑过]

guafafd

以下是引用mikejia在2004-12-21 13:43:00的发言：

sorry

from 81 to 99

81 82 83 84 ....89

90 91 ... 99

8 and 9 aren't prime number

thanks!