CODE EXAMPLE FOR PYTHON

Sum of all the multiples of 3 or 5

const findSum = n => {
  let countArr = []
  
  for(let i = 0; i <= n; i++) if(i % 3 === 0 || i % 5 === 0) countArr.push(i) 
  return countArr.reduce((acc , curr) => acc + curr)
}
console.log(findSum(5))

// With love @kouqhar