## How to solve a hard number system question for CAT confidently and quickly 8

The leftmost digit of a natural number at least 7 digit long is 3. When the leftmost digit is dropped, the number formed by the rest of the digits becomes $\frac{1}{5}$th of the original number. What is the product of the non-zero digits of the original number?

**Hint:** Solve this 8th hard number system question for CAT using the very basic concepts intelligently.