freeCodeCamp/guide/english/certifications/coding-interview-prep/project-euler/problem-8-largest-product-in-a-series/index.md

---
title: 'Problem 8:  Largest product in a series'
---
# Problem 8: Largest product in a series

---
## Problem Explanation

- In this challenge we need to get the largest product of `n` cosnecutive numbers.
- We can use the sliding window method to solve this problem.
- Steps to follow:
  1. Select the first n consecutive numbers.
  2. Find their product.
  3. Compare it to the maximum product yet.
  4. Move the pointer by 1 element.
  5. Repeat the process.
 - This algorithm's big O is **O(n\*m)** where n is the length of the array and m is the number of consecutive elements.


---
## Solutions
<details><summary>Solution 1 (Click to Show/Hide)</summary>

```js
function largestProductinaSeries(n) {
  let thousandDigits = [
    7,
    3,
    1,
    6,
    7,
    1,
    7,
    6,
    5,
    3,
    1,
    3,
    3,
    0,
    6,
    2,
    4,
    9,
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    1,
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    6,
    7,
    4,
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    5,
    7,
    5,
    3,
    0,
    4,
    2,
    0,
    7,
    5,
    2,
    9,
    6,
    3,
    4,
    5,
    0
  ];

  let len = n;
  let prod = 1,
    max = 1;
  while (len < thousandDigits.length) {
    prod = 1;

    //Looping and computing products of n numbers
    for (let i = len - n; i < len; i++) {
      prod *= thousandDigits[i];
    }
    if (prod > max) max = prod;
    len++;
  }
  return max;
}

console.log(largestProductinaSeries(13));
```

#### Relevant Links

- [Sliding Window Technique](https://www.geeksforgeeks.org/window-sliding-technique/)

</details>