Question 15
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 note for this self-study exercise:** A six-digit code has a nonzero first digit. Enter only the first three digits. The supplied solution contains arithmetic errors identified 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 note for this self-study exercise:** A six-digit code has a nonzero first digit. Enter only the first three digits. The supplied solution contains arithmetic errors identified below.