Imagine you have a magic box that can do math. If you put a number into the box, it gives you a new number as an answer. But this magic box also has some special rules that it follows when it does the math.
One of these rules is called Bloch's formula. It tells you how to do math with really big numbers that have a lot of repeating patterns in them. It's like if you had a number that was 123123123123123 and you wanted to add it to another number, but that other number also had a lot of repeating patterns in it.
Bloch's formula helps you figure out what the answer is without having to actually add all those repeating patterns together, one by one. This makes it much easier and faster to do math with big numbers that have repeating patterns.
So, in short, Bloch's formula is a special way of doing math with big numbers that have repeating patterns in them. It makes math easier and faster and helps you get the answer without having to do a lot of time-consuming adding.