How many different signals can be made by 4 flags from 6 flags of different colours?

Explanation

To solve the problem of how many different signals can be made by using 4 flags from a total of 6 flags of different colors, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Total Flags and Selection**:
We have 6 flags of different colors and we need to select 4 flags to create signals.

2. **Determine the Arrangement**:
...