Question 6
Example 3. Gina’s 6-digit postal code has the following interesting properties:
- It is the same number if your read it from right to left.
- It is a multiple of 9.
- If you remove the first and last digits, the only prime factor of the remaining 4-digit number is 11.
Find the first 3 digits of Gina’s postal code.
**Editorial input convention:** Treat the code as a six-digit integer and the remaining middle as a four-digit integer, with no leading zero in either. Enter only the first three digits of the code that satisfies all stated conditions. The printed source solution has arithmetic errors, disclosed below.
- It is the same number if your read it from right to left.
- It is a multiple of 9.
- If you remove the first and last digits, the only prime factor of the remaining 4-digit number is 11.
Find the first 3 digits of Gina’s postal code.
**Editorial input convention:** Treat the code as a six-digit integer and the remaining middle as a four-digit integer, with no leading zero in either. Enter only the first three digits of the code that satisfies all stated conditions. The printed source solution has arithmetic errors, disclosed below.