Skip to content / Đến nội dung
ThichHocToan.com

1991 AMC 12 Question 17

AMC12 · 1991 AMC 12

Question 17

A positive integer $N$ is a palindrome if the integer obtained by reversing the sequence of digits of $N$ is equal to $N.$ The year $1991$ is the only year in the current century with the following two properties:

(a) It is a palindrome.

(b) It factors as a product of a $2$-digit prime palindrome and a $3$-digit prime palindrome.

How many years in the millennium between $1000$ and $2000$ (including the year $1991$) have properties (a) and (b)?
  1. $1$
  2. $2$
  3. $3$
  4. $4$
  5. $5$