ELI5: Explain Like I'm 5

Splitting principle

Okay, so splitting principle is like when you have some candy to share with your friends, but you want to make sure it's fair and everyone gets an equal amount.

Let's say you have 10 candies and 2 friends, and you want to split it equally. You could give 5 candies to one friend and 5 candies to the other friend. Or you could give 4 candies to each friend and keep 2 for yourself.

But what if you have more friends or more candies? It might be harder to figure out how to split it evenly. That's where the splitting principle comes in.

The splitting principle is a way to figure out how many ways you can split a larger number of things into smaller groups. It's like a math formula.

Let's say you have 12 candies and 4 friends. You can use the splitting principle to figure out how many ways you can split the candies so that each friend gets the same amount.

Here's how it works:

- First, you count up the total number of things you have (in this case, candies) and write it as a fraction. So you have 12 candies, which you can write as 12/1.
- Then you figure out how many groups you want to split it into (in this case, 4 friends). You write that number as a factor of the denominator of the fraction. So the denominator is 1, and 4 is a factor of 1 (because 4 x 1 = 4). So you write it as 1/4.
- Next, you add up all the possible ways you can split the candies into 4 groups of equal size. This is where it gets a bit complicated, but don't worry! You can use a trick called factorial. Factorial is just a fancy math word for multiplying a number by all the numbers below it.

So for 4 friends, you can list out all the possible ways you can split the 12 candies:

- 3 candies for each friend (3 x 4 = 12)
- 2 candies for each friend, with 4 candies left over (2 x 4 + 4 = 12)
- 1 candy for each friend, with 8 candies left over (1 x 4 + 8 = 12)

Now you use factorial to add up all of these possibilities.

- The first one (3 candies for each friend) is just 1 possibility.
- The second one (2 candies each, with 4 left over) is a bit trickier. You have to figure out how many ways you can arrange those 4 leftover candies. You can use factorial for that: 4! = 4 x 3 x 2 x 1 = 24. So there are 24 ways you can split the candy in this way.
- The third one (1 candy each, with 8 left over) is also a bit trickier. You have to figure out how many ways you can arrange those 8 leftover candies. You use factorial again: 8! = 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 40,320. That's a big number!

So to get the total number of possibilities, you add up all the factorials:

1 + 24 + 40,320 = 40,345

That's how many ways you can split 12 candies into 4 equal groups using the splitting principle!

So in conclusion, the splitting principle is a way to figure out how many ways you can split a larger number of things (like candy) into smaller groups (like friends), so that each group gets the same amount. You use a fancy math formula that involves fractions, factors, and factorial.
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