If I said “3!“, would you think the 3 is really excited, or that you have to shout the number?
In fact, it’s a mathematical operation called factorials, and boy are they fun! They may seem complicated at first, but they’re really a very basic concept. The exclamation point behind a number means that you multiply that number by each successively lower number, in order, until you get to one.
So 3! would be 3 x 2 x 1 = 6.
Take a look at the video for an explanation of how factorials work and how they can be used.
Download Student Worksheet & Exercises
Can you see how factorials start to get really big, really quickly? The card deck is a really great example of this, because with 52 cards the factorial is 52!, which is a HUGE number. There are literally trillions and trillions and trillions of ways to arrange those cards.
Does 0! = 1 make sense to you? If not, that’s okay. Just memorize this fact and tuck it away for later. It will come in handy some day in algebra and maybe even for calculus!
Exercises
- 6!
- 6!/4!
- How many ways can seven different cards arranged uniquely?
- 0! x 4!
- 3! x 4!
- 1! x 5!
- 2! x 0 x 6!
- 2! x 4!
- 3! x 2!
- 5! x 0! x 1! x 2!