[Javascript] Calculate a percentage of something [quick]

Cut and paste the below into the section of your page:

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<SCRIPT language=JavaScript>

function perc1() {
 a = document.form1.a.value/100;
 b = a*document.form1.b.value;
 document.form1.total1.value = b
 }
function perc2() {
 a = document.form1.c.value;
 b = document.form1.d.value;
 c = a/b;
 d = c*100;
 document.form1.total2.value = d
 }
//-->
</SCRIPT>

<FORM name=form1>
<TABLE cellSpacing=1 cellPadding=1 border=1>
  <TBODY>
  <TR>
    <TD align=middle colSpan=3><B><FONT size=4>Percentage Calculator</FONT></B>
      </TD>
  <TR>
    <TD>What is <INPUT size=5 name=a> % of <INPUT size=5 name=b>?</TD>
    <TD>Answer: <INPUT maxLength=40 size=5 name=total1></TD>
    <TD><INPUT onclick=perc1() type=button value=Calculate></TD>
  <TR>
    <TD><INPUT size=5 name=c> is what percent of <INPUT size=5
name=d>?</TD>
    <TD>Answer: <INPUT size=5 name=total2> %</TD>
    <TD><INPUT onclick=perc2() type=button value=Calculate></TD>
  <TR>
    <TD align=middle
colSpan=3><INPUT type=reset value=Reset></TD></TR></TBODY></TABLE></FORM>