Validated numerics is like making sure your answers in math are correct. Imagine you are doing a math problem and your teacher asks you for the answer. You could just give them a guess, but that might not be right. Instead, you can use validated numerics to make sure you have the right answer.
This works by starting with some information that you know is true (like the formula for solving the problem) and using that to figure out a range of numbers that the answer could be. Then you can test this range of numbers to see if any of them work. If a number in the range works, then you can be sure that it is the right answer.
This is really helpful in situations where it's important to have a very accurate answer. For example, if you're designing a bridge, you want to make sure the weight limit is accurate so that the bridge doesn't collapse. Validated numerics can help you make sure you have the right weight limit. It can also be used in science or engineering to make sure that calculations are correct.
So, validated numerics are like a way of double-checking your answers to make sure they're correct, using a range of numbers to find the correct answer.