function handleButton(event) {
  var box = document.getElementById('cal-box');

  if (!(box === document.activeElement)) {
    // Solve
    if(autoclear){
      if(lastNum == '=') {
        box.value = '';
      }
    }
    if (event.target.id == '=') {
      var temp = box.value.replace(/ln\(/g, 'log(');
      answer = math.eval(temp);
      if (!isNaN(answer)) {
        box.value = answer;
        if(autoclear){
          lastNum = '=';
        } else {
          lastNum = answer;
        }
      }
    // Clear
    } else if (event.target.id == 'clr') {
      box.value = '';
      lastNum = 'new';
    // Backspace
    } else if (event.target.id == '<-') {
      box.value = box.value.substring(0, box.value.length - 1);
      lastNum = box.value.charAt(box.value.length - 1);
    // Numbers
    } else if (/[0-9]/.test(event.target.id)) {
      box.value = box.value + event.target.id;
      lastNum = event.target.id;
    // Symbols
    } else if (/[-/*+.]/.test(event.target.id)) {
      if(!(/new|[-/*+.]/.test(lastNum))){
        box.value = box.value + event.target.id;
        lastNum = event.target.id;
      }
    } else if (event.target.id == '^'){
      if (/[0-9]|\)/.test(lastNum)) {
        box.value = box.value + '^(';
      }
    } else if (/[\(\)]/.test(event.target.id)) {
      box.value = box.value + event.target.id;
      lastNum = event.target.id;
    // Trig Functions
    } else if (/sin|cos|tan|cot|sqrt|e\^|ln/.test(event.target.id)) {
      box.value = box.value + event.target.id + '('
      lastNum = '(';
    } else if (/pi/.test(event.target.id)){
      box.value = box.value + '(pi)';
      lastNum = ')';
    }
    this.blur();
  }
}