GWD 17-16

casualwalk

Q16:The three-digit integer kss is the sum of the two-digit integers ks and rs, where k, r, and s are the digits of the integers. Which of the following must be true?

I. k = 2

II. r = 9

III. s = 5

A. I only

B. II only

C. III only

D. I and II

E. II and III

Answer: B

这题该怎么算比较好呀？

rainyliu

s只能的0因为只有0+0还等于0

而ks+rs=kss这个式子中两个两位数相加所得出的三位数百位上肯定是1

也就是说，kss=100, k=1,带到式子中可以推出r=9

jhiiool

ks+rs=kss　因为Ｋ在百位，Ｓ＋Ｓ＝Ｓ，所以，Ｋ＝１，Ｓ＝０，因此Ｒ＝９