GCD/LCM Calculator

This calculator can quickly determine the Greatest Common Factor and Least Common Multiplier between two or three numbers.

1. Copy the coding into the HEAD of your HTML document
2. Add the last code into the BODY of your HTML document

<script type=”text/javascript”>
<!– This script and many more are available free online at –>
<!– The JavaScript Source!! http://javascriptsource.com –>
<!– Original: Seamus Yim –>

<!– Begin
function go(input1,input2,input3){
  if (document.form1.text3.value!=””){
    document.form1.answer.value=hcf(hcf(input1,input2),input3);
    document.form1.answer2.value=lcm(lcm(input1,input2),input3);
  } else {
    document.form1.answer.value=hcf(input1,input2);
    document.form1.answer2.value=lcm(input1,input2);
  }
}

function hcf(text1,text2){
  var gcd=1;
  if (text1>text2) {text1=text1+text2; text2=text1-text2; text1=text1-text2;}
  if ((text2==(Math.round(text2/text1))*text1)) {gcd=text1}else {
   for (var i = Math.round(text1/2) ; i > 1; i=i-1) {
    if ((text1==(Math.round(text1/i))*i))
     if ((text2==(Math.round(text2/i))*i)) {gcd=i; i=-1;}
   }
  }
  return gcd;
}

function lcm(t1,t2){
  var cm=1;
  var f=hcf(t1,t2);
  cm=t1*t2/f;
  return cm;
}
//  End –>
</script>

<div align=”center”>
<form name=”form1″>
First Number:  <input type=”text” name=”text1″ size=”3″>
  Second Number:  <input type=”text” name=”text2″ size=”3″><br>
  Third Number (<em>not required</em>):  <input type=”text” name=”text3″ size=”3″>
<br><br>
<input type=”button” value=”Find GCF and LCM” onclick=”go(eval(document.form1.text1.value),eval(document.form1.text2.value),eval(document.form1.text3.value))”>
<br><br>
Greatest Common Factor (GCF):   <input type=”text” name=”answer” size=”3″ readonly>
<br>
Least Common Multiplier (LCM):   <input type=”text” name=”answer2″ size=”3″ readonly>
</form>
</div>

<p><center>
<font face=”arial, helvetica” size”-2″>Free JavaScripts provided<br>
by <a href=”https://javascriptsource.com”>The JavaScript Source</a></font>
</center><p>