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Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today. # Can someone explain why the functions end up with the value 65 in the last example?

Hi, in the example of CPS (continuation-passing style), they give an example of functions that takes callbacks as arguments. Could someone be so kind and explain to my how the functions end up with the value 65 in the end? I've tried to go through the sequences but I'm not really getting it.

```function add(x, y, callback) {
// The x will be 5 and y will be 10 so sum will be 15
// The sum value will be forwarded to callback and in callback we're calling subtract
callback(x + y)
}
function subtract(x, y, callback) {
// The x will be 15 and y will be 2 so subtraction will be 13
// The subtracted value will be forwarded to callback and in callback we're calling mutiply
callback(x - y);
}
function multiply(x, y, callback) {
// The x will be 13 and y will be 5 so product will be 65
// The product value will be forwarded to callback and the n will be 65
callback(x * y);
}
function calculate(x, callback) {
// The x will be 5
//Value of 5 will be forwarded to callback & in callback we're calling add with 5
callback(x);
}

calculate(5, (n) => {
subtract(n, 2, (n) => {
multiply(n, 5, (n) => {
console.log(n); // 65
});
});
});
});
```

Hope it helps. Let me know if you have still any doubts.

Thanks