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The calculator program should be able to perform a math operation on a number. We should be able to give a calculator a number, have it perform a task on it like multiplication, then print a result.

Currently, we have no way to give a function a number. To do this, we can use parameters. Parameters are variables that we can set when we call the function. For example:

``````function multiplyByThirteen(inputNumber) {
console.log(inputNumber * 13);
}

multiplyByThirteen(9);
// Output: 117
``````
1. We added `inputNumber` within the parentheses of the `multiplyByThirteen` function. `inputNumber` is a parameter.
2. Inside the `multiplyByThirteen` function, we use `console.log` to print the `inputNumber` by `13`.
3. When we call the `multiplyByThirteen` function on the last lines, we set the `inputNumber` parameter. For instance, `multiplyByThirteen(9)` calls the `multiplyByThirteen` function, and sets `inputNumber` as `9`. Then, inside the block of the `multiplyByThirteen` function, `9` is multiplied by `13`, resulting in `117` printing to the console.
4. Note on terminology: `inputNumber` is a parameter, but when we call `multiplyByThirteen(9)`, the `9` is called an argument. Therefore, arguments are provided when you call a function, and parameters receive arguments as their value. So, `inputNumber` is a parameter and its value is the argument `9`, since we wrote `multiplyByThirteen(9)`.

Parameters let us write logic inside functions that can be modified based on when we call the function, which will help make our functions more flexible.

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