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JavaScript

function convertMinsToHrsMin(minutes) {
  
  var str = '';
  var h = Math.floor(minutes / 60);
  var m = minutes - (h * 60);
  h = h < 10 ? '0' + h : h;
  m = m < 10 ? '0' + m  : m;
  if (h > 12) {
  	h = h - 12;
    str = "PM";
  } else {
  	str = "AM";
  }
  return h + ":" + m + " " + str;

}

alert(convertMinsToHrsMin(840));