Cardinality

Cardinality is a fancy word that helps us count the number of things in a group or set.

Imagine you have a box of toys. If you want to know how many toys are in the box, you can count them one by one. That's called "counting cardinality."

But what if you have a lot of boxes of toys? Maybe you have one box of cars, one box of dolls, and one box of blocks. Each box has a different number of toys inside. That's where the term "set cardinality" comes in.

With set cardinality, we don't have to count each toy in each box. Instead, we just look at the number of boxes and how many toys are in each box. We can use math symbols like " | | " to represent the number of objects in a set.

So, if we have a box of cars with 5 toy cars inside, we can represent that set like this: | {car1, car2, car3, car4, car5} |

And if we have three different boxes of toys with different amounts of toys in each, we can represent them like this:

| {car1, car2, car3, car4, car5} , {doll1, doll2, doll3} , {block1, block2} |

That way, we know how many boxes we have and how many toys are in each box without having to count every single toy again and again. That's the magic of cardinality!