Okay, let's imagine you have a bunch of coins: 1 penny, 1 nickel, 1 dime, and 1 quarter.
Now we want to use these coins to create different numbers by adding them up. For example, if we use the penny and the nickel, we get 6 cents. If we use all four coins, we get 41 cents.
We can represent these numbers using a set of natural numbers. The set of natural numbers is just a fancy way of saying all the positive whole numbers like 1, 2, 3, 4, 5, and so on.
So for our coin example, we can represent the numbers we can make like this:
{2, 5, 6, 10, 11, 15, 16, 20, 21, 25, 26, 41}
Now let's imagine we want to use these numbers to create a circuit. A circuit is like a path that goes through different numbers in the set.
We can start at any number and move to another number by adding or subtracting one of the coins. For example, if we start at 2, we can move to 6 by adding a penny and a nickel.
We can keep doing this, moving from number to number until we create a circuit that is like a loop.
So circuits over sets of natural numbers are just like creating paths that connect different numbers in a set, using a series of operations like addition and subtraction. It's like playing a game with the coins, trying to create different numbers and see how they connect to each other.