# Calculating least common of a range JavaScript

We are required to write a function that takes in an array of two numbers a and b (a >= b) and returns the least common multiple of all the numbers between [a, b].

## Approach

We will first write a basic function that calculates the least common multiple of two numbers, once we have that we will recursively call it over the numbers that fall between [a, b] and finally return the result.

## Example

const lcm = (a, b) => {
let min = Math.min(a, b);
while(min >= 2){
if(a % min === 0 && b % min === 0){
return (a*b)/min;
};
min--;
};
return (a*b);
};
const leastCommonMultipleInRange = (arr, len = arr, res = 1) => {
if(len <= arr){
return leastCommonMultipleInRange(arr, len+1, lcm(res, len));
};
return res;
};
console.log(leastCommonMultipleInRange([6, 8]));
console.log(leastCommonMultipleInRange([6, 18]));
console.log(leastCommonMultipleInRange([1, 8]));
console.log(leastCommonMultipleInRange([10, 25]));

## Output

The output in the console will be −

168
12252240
840
26771144400