P-adic analysis is like playing with numbers but in a different way than you're used to. It's like building with blocks, but instead of using regular blocks, you use blocks that can be as small as you want. Imagine having a bunch of blocks that get smaller and smaller, all the way down to tiny little specks. That's what p-adic numbers are like.
These numbers are called p-adic because they have to do with a special number called p. When we use normal numbers, we count in tens (0,1,2,3...9) and then carry over to the next digit. But with p-adic numbers, we count in a different way, depending on the p we're using. So if p=2, we count in twos (0,2,4,6...), and if p=3, we count in threes (0,3,6,9...). This might sound strange, but it follows its own rules and can be very useful.
We can do calculations in p-adic numbers, just like we can with regular numbers. But because p-adic numbers get smaller and smaller, something cool happens. If we have a sequence of numbers that are constantly getting closer and closer to each other, they eventually become the same number in the p-adic world. This is different from regular numbers, where the sequence might just get really close but never actually reach the same number.
So why is this useful? Well, p-adic analysis is used in lots of fields like physics and cryptography because it helps us solve problems that regular numbers can't. It's like having a different set of tools that work better in certain situations. And just like playing with blocks can help you learn how to build things, playing with p-adic numbers can help you learn how to solve problems in new and different ways.