If a number like Pi is infinite, how do we know each decimal that is newly calculated is valid?

Question

Not a mathematician here at all so perhaps my question is phrased incorrectly.

Let’s say through thorough testing in reality, we can prove with certainty Pi is correct up until 5 decimal places,

3.14159

The computers that are calculating Pi to an endless degree, how do they validate new values that are calculated as correct and cannot be otherwise?

In: 434

Answer 1

Very smart people has found ways to represent pi as a sum of numbers. This sum they created has a pattern, but it has infinite sums, that results in pi. Because of that we are able to predict each decimal, but because the sum is infinite, so is the decimals for pi.