ELI5: Explain Like I'm 5

Cauchy's limit theorem

Imagine you have a bunch of numbers and you want to know if they are getting closer and closer to a certain number, even if they never actually reach it. This is what Cauchy's limit theorem talks about.

It says that if you have a sequence of numbers that are getting closer and closer to a certain number, then you can find a number (called the limit) that the sequence is approaching.

For example, imagine you have the sequence 1, 1.5, 1.75, 1.875, 1.9375... This sequence is getting closer and closer to the number 2, even though it never actually reaches it. So, we say that the limit of this sequence is 2.

Now imagine you have another sequence that is getting closer and closer to a different number, say 3.5. Then, according to Cauchy's limit theorem, there must be a number that both sequences approach. This number is called the limit of the two sequences.

Cauchy's limit theorem is important in mathematics because it helps us understand how numbers behave when we have a lot of them. It allows us to find patterns and make predictions, even when we don't have all the information we need.