Ostrowski's theorem

Ostrowski's theorem is a special math rule used by number experts for something called numerical analysis. It helps to figure out how accurate a number is when we use what's called a decimal number system.

So when we count numbers, we start with 1, then 2, then 3, and so on. But sometimes, we also use numbers after a decimal point like 1.5 or 2.89. These are called decimals.

Now, there are different ways to write a number when we use decimals. And sometimes, we want to know if a certain way of writing a number is close to the actual number or not. That's where Ostrowski's theorem comes in handy.

It tells us that if we use a specific way of writing a number called the "base" and if we know another "size" number which measures how big or small the number is, then we can accurately figure out how close our way of writing the number is to the real number.

So basically, Ostrowski's theorem helps us make sure we are using the right way of writing decimals so that we can know exactly how close we are to the actual number we are trying to write down.