A hall has 10 gates. In how many ways can a man enter the hall through one gate and come out through a different gate ?

Explanation

To solve the problem of how many ways a man can enter a hall through one gate and come out through a different gate, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Total Number of Gates**:
The hall has a total of 10 gates.

2. **Choose the Gate to Enter**:
...