Originally Posted by

**Soroban** Hello, nycmath!

Usually there are no "key words" to warn us.

You must call on your "life experience" to interpret the situation.

"Form a committee of 3 people from 12 members."

Does the order of their names make a difference?

No, $\displaystyle \{A,B,C\}$ is the same committee as $\displaystyle \{B,C,A\}.$

This is a Combination.

"Form 3-letter words from the letters $\displaystyle \{A,C,O,T\}.$

Does the order of the letters make a difference?

Yes, $\displaystyle ACT$ is not the same as $\displaystyle C\!AT.$

This is a Permutation.

An amusing observation . . .

A *combination lock* has a set of three numbers used for unlocking.

But the three numbers must applied in a specific order.

So shouldn't it be called a *permutation lock*?