---
title: Sum All Odd Fibonacci Numbers
---
 Remember to use **`Read-Search-Ask`** if you get stuck. Try to pair program  and write your own code 
###  Problem Explanation:
You will need to gather all the **Fibonacci** numbers and then check for the odd ones. Once you get the odd ones then you will add them all. The last number should be the number given as a parameter if it actually happens to be an off Fibonacci number.
#### Relevant Links
*   Fibonacci number
##  Hint: 1
To get the next number of the series, you need to add the current one to the previous and that will give you the next one.
> _try to solve the problem now_
##  Hint: 2
To check if a number is even all you have to check is if `number % 2 == 0`.
> _try to solve the problem now_
##  Hint: 3
As you get the next odd one, don't forget to add it to a global variable that can be returned at the end. `result += currNumber;` will do the trick.
> _try to solve the problem now_
## Spoiler Alert!

**Solution ahead!**
##  Basic Code Solution:
    function sumFibs(num) {
        var prevNumber = 0;
        var currNumber = 1;
        var result = 0;
        while (currNumber <= num) {
            if (currNumber % 2 !== 0) {
                result += currNumber;
            }
            currNumber += prevNumber;
            prevNumber = currNumber - prevNumber;
        }
        return result;
    }
    // test here
    sumFibs(4);
 Run Code
### Code Explanation:
*   Create a variable to keep record of the current and previous numbers along with the result that will be returned.
*   Use a while loop to make sure we do not go over the number given as parameter.
*   We use the modulo operand to check if the current number is odd or even. If it is even, add it to the result.
*   Complete the Fibonacci circle by rotating getting the next number and swapping values after.
*   Return the result.
#### Relevant Links
*   JS while Loop
##  Intermediate Code Solution:
    function sumFibs(num) {
        // Perform checks for the validity of the input
        if (num < 0) return -1;
        if (num === 0 || num === 1) return 1;
        // Create an array of fib numbers till num
        const arrFib = [1, 1];
        let nextFib = 0;
        
        // We put the new Fibonacci numbers to the front so we
        // don't need to calculate the length of the array on each
        // iteration
        while((nextFib = arrFib[0] + arrFib[1]) <= num) {
            arrFib.unshift(nextFib);
        }
        // Sum only the odd numbers and return the value
        // First, reverse the array to avoid starting acc with the first/greater number when it's even
        return arrFib.reverse().reduce((acc, curr) => {
            return acc + curr * (curr % 2);
        });
    }
    // test here
    sumFibs(4);
 Run Code
### Code Explanation:
*   Create an array of fibonacci numbers till **num**.
*   Use `reduce()` method to find the sum of odd members of array.
*   Return the sum.
#### Relevant Links
*   JS Array Prototype Push
*   JS For Loops Explained
*   JS Array Prototype Reduce
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