# Learn Recursion by Building a Decimal to Binary Converter - Step 109

Hello,

Quick question

why in the code I need launch

`decimalToBinary(inputInt)` and not directly `decimalToBinary()`

and then why do I need the “input” in `const decimalToBinary = (input) => {};`

then why something like this is not working :

``````convertBtn.addEventListener("click", checkUserInput);

const checkUserInput = () => {
const b = parseInt(numberInput.value);

if (!numberInput.value || isNaN(b)) {
return;
}

if (b === 5) {
showAnimation();
return;
}

result.textContent = decimalToBinary();
numberInput.value = "";
}

const decimalToBinary = () => {
const a = parseInt(numberInput.value)
if (a === 0 || a === 1) {
return String(a);
} else {
const c = (decimalToBinary((a / 2)) + (a % 2));

return String(c);

}
};
``````

I belive I’ve miss the key information at some point
thanks

### Challenge Information:

Learn Recursion by Building a Decimal to Binary Converter - Step 109

because the function needs a number to convert, and that is given to the function as the argument

to use the value of the arguments you need to give a parameter when you create the function

the function is missing the argument, the function doesn’t know what number to convert