---
title: Sum All Numbers in a Range
---
# Sum All Numbers in a Range
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## Problem Explanation
You need to create a program that will take an array of two numbers who are not necessarily in order, and then add not just those numbers but any numbers in between. For example, [3,1] will be the same as `1+2+3` and not just `3+1`
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## Hints
### Hint 1
Use `Math.max()` to find the maximum value of two numbers.
### Hint 2
Use `Math.min()` to find the minimum value of two numbers.
### Hint 3
Remember to that you must add all the numbers in between so this would require a way to get those numbers.
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## Solutions
Solution 1 (Click to Show/Hide)
```javascript
function sumAll(arr) {
var max = Math.max(arr[0], arr[1]);
var min = Math.min(arr[0], arr[1]);
var temp = 0;
for (var i = min; i <= max; i++) {
temp += i;
}
return temp;
}
sumAll([1, 4]);
```
#### Code Explanation
* First create a variable to store the max number between two.
* The same as before for the Smallest number.
* We create a temporary variable to add the numbers.
Since the numbers might not be always in order, using `max()` and `min()` will help organize.
#### Relevant Links
* Math.max()
* Math.min()
* For Loops
Solution 2 (Click to Show/Hide)
```javascript
const sumAll = arr => {
// Buckle up everything to one!
const startNum = arr[0];
const endNum = arr[1];
// Get the count of numbers between the two numbers by subtracting them and add 1 to the absolute value.
// ex. There are |1-4| + 1 = 4, (1, 2, 3, 4), 4 numbers between 1 and 4.
const numCount = Math.abs(startNum - endNum) + 1;
// Using Arithmetic Progression summing formula
const sum = ((startNum + endNum) * numCount) / 2;
return sum;
};
```
#### Code Explanation
* The formula for calculating the sum of a continuous range is "(startNum + endNum) * numCount / 2".
* arr[0] and arr[1] can either be startNum or endNum, order doesn't matter.
* We can get the count of numbers in range by "Math.abs(arr[0] - arr[1]) + 1".
* Applying the formula by plugging in the numbers.
#### Relevant Links
* Array.sort()
* Arithmetic Progression summing formula
* ES6 arrow function
Solution 3 (Click to Show/Hide)
```javascript
function sumAll(arr) {
var sum = 0;
for (var i = Math.min(...arr); i <= Math.max(...arr); i++) {
sum += i;
}
return sum;
}
sumAll([1, 4]);
```
#### Code Explanation
* Creating a variable sum to store the sum of the elements.
* Starting iteration of the loop from min element of given array and stopping when it reaches the max element.
* Using a spread operator (...arr) allows passing the actual array to the function instead of one-by-one elements.
#### Relevant Links
* Spread Operator
* Using Spread Operator in Math.max()