Answer: 6
Explanation:
Given : The number of friends : 3
If we introduce one by one , then the number of ways to introduce them is given by permutations .
We can choose first friend in 3 ways , second in 2 and the third in one way.
Then , the number of ways of introducing 3 friends one at a time is given by :-

Therefore, the number of ways of introducing 3 friends = 6