Question

A safety locker in a jewel shop requires a 4 digit unique code. The code has the digits from 0 to 9. How many unique codes are possible ?

Answer 1

The unique code has 4 digits.

Each digit is formed using any of the 10 numbers from 0 to 9.

∴ Single digit number can be formed in 10 ways.

A double digit number can be formed in 10 × 10 ways.

A three digit number can be formed in 10 × 10 × 10 ways.

A four digit number can be formed in 10 × 10 × 10 × 10 ways. = 10,000 ways