Cindy is thinking of a number which is 4 less than the square of a positive integer. The number
has the property that it has two 2-digit prime factors. What is the smallest possible value of
Cindy's number?
Choose the correct choice from the following answers.
A) 221
B) 231
C) 241
D) 251
E) 261
Let x be Cindy's number. Then x = n2-4 = (n-2)(n+2) for some positive integer   n. Since n + 2 and n - 2 differ by 4, our goal is hence to find two 2-digit prime numbers which   dier by 4. By writing the first few prime numbers, we find that the pair (13,17) is the smallest   pair possible, which gives us a value of 13 * 17= 
<gadget id="calculator">13 * 17</gadget>
<output>221</output>
221 .   correct answer 221
<result>A</result>
Cindy is thinking of a number which is 4 less than the square of a positive integer. The number
has the property that it has two 2-digit prime factors. What is the smallest possible value of
Cindy's number?