Math.sqrt()

Math.sqrt(x) ;

<script language='JavaScript' type='text/JavaScript'>
<!--
document.write(Math.sqrt(4)); // output is 2
document.write("<br>");
document.write(Math.sqrt(64)); // output is 8
document.write("<br>");
document.write(Math.sqrt(9)); // output is 3
document.write("<br>");
document.write(Math.sqrt(27)); // output is 5.196152422706632
document.write("<br>");
document.write(Math.sqrt(0.36)); // output is 0.6
document.write("<br>------------<br>");
document.write(Math.sqrt(-64)); // output is Nan
document.write("<br>");
document.write(Math.sqrt(-9)); // output is NaN
//-->
</script>