Given 4 flags of different colours, how many different signals can be generated, if a signal requires the use of 2 flags one below the other?

Explanation

To solve the problem of how many different signals can be generated using 2 flags from a set of 4 flags of different colors, we can follow these steps:

### Step 1: Choose 2 Flags from 4 Flags
We need to select 2 flags from the 4 available flags. The number of ways to choose 2 flags from 4 can be calculated using the combination formula:

\[ \text{Number of ways to choose 2 flags} = \binom{4}{2} \]
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