The number of 5-digit number that can be made using the digits 1 and 2 and in which at laest one digits is different, is

Options

A. 30
B. 31
C. 32
D. none of these

Explanation

To solve the problem of finding the number of 5-digit numbers that can be made using the digits 1 and 2, where at least one digit is different, we can follow these steps:

### Step 1: Calculate the total number of 5-digit combinations
Each digit in the 5-digit number can either be a 1 or a 2. Therefore, for each of the 5 positions, we have 2 choices (1 or 2). The total number of 5-digit combinations can be calculated as:

\[ \text{Total combinations} = 2^5 \]
...