Do sekce <BODY> umístěte:
<SCRIPT language=JavaScript>
<!--
n=[0,1,2,3,4,5,6,7,8,9];
z=["+","-","*","/","."];

function c(f) { f.vyraz.value=eval(f.vyraz.value); }
function i(f,string) { f.vyraz.value+=string; }
function d(f) { f.vyraz.value=""; }
// -->
</SCRIPT>

<FORM>
<TABLE border=1 cellPadding=0 cellSpacing=0>
<TBODY>
<TR>
<TD colSpan=4><INPUT name=vyraz size=21
style="FONT-SIZE: 10px"> </TD></TR>
<TR>
<TD><INPUT onclick=i(form,n[7]); type=button value=" 7 "> </TD>
<TD><INPUT onclick=i(form,n[8]); type=button value=" 8 "> </TD>
<TD><INPUT onclick=i(form,n[9]); type=button value=" 9 "> </TD>
<TD align=left><INPUT onclick=i(form,z[3]); type=button value=" / ">
</TD></TR>
<TR>
<TD><INPUT onclick=i(form,n[4]); type=button value=" 4 "> </TD>
<TD><INPUT onclick=i(form,n[5]); type=button value=" 5 "> </TD>
<TD><INPUT onclick=i(form,n[6]); type=button value=" 6 "> </TD>
<TD align=left><INPUT onclick=i(form,z[2]); type=button value=" * ">
</TD></TR>
<TR>
<TD><INPUT onclick=i(form,n[1]); type=button value=" 1 "> </TD>
<TD><INPUT onclick=i(form,n[2]); type=button value=" 2 "> </TD>
<TD><INPUT onclick=i(form,n[3]); type=button value=" 3 "> </TD>
<TD align=left><INPUT onclick=i(form,z[1]); type=button value=" - ">
</TD></TR>
<TR>
<TD colSpan=3><INPUT onclick=i(form,n[0]); type=button value=" 0 ">
</TD>
<TD align=left><INPUT onclick=i(form,z[0]); type=button value=" + ">
</TD></TR>
<TR>
<TD colSpan=3><INPUT onclick=c(form); type=button value=" = ">
<INPUT onclick=d(form); size=3 type=button value=" C "> </TD>
<TD align=left><INPUT onclick=i(form,z[4]); type=button value=" .">
</TD>