Untitled

function expandedForm(num) {
  
  let res = []
  
  let i = 1
  
  while(num >= 1){
    
    let lastDigit = num % 10
    if(lastDigit) res.unshift(lastDigit * i)
    
    i *= 10
    num = Math.floor(num / 10)
  }
  
  return res.join(" + ")
}