How do I square a number's digits?

Question

How do I square a number's digits? e.g.:

square(21){};

should result in 41 instead of 441

Answer 1

function sq(n){
var nos = (n + '').split('');
var res="";
for(i in nos){
  res+= parseInt(nos[i]) * parseInt(nos[i]);
}

return parseInt(res);
}

var result = sq(21);
alert(result)