Plz help for this Vectorial

i want when i write 5 or something the result shows like that
5 x 4 x 3 x 2 x 1 = (Answer) . I thimk this called victorial or vactoria?
Plz help me i want to write with javascript

 

Factorial...
Is it something like below?
function fact(a){
var b = a;
for (var i=a-1; i>0; i--) b *= i;
return b;
}

 

First of all Its not Vatorial its called Factorial. Its an important concept of mathematics and calculation. Now According to your problem you can implement this like
< language="JavaScript">
Function fact(var num)
{
var b=1;
for(var i=1;i<=num;i++)
{
b=b*i;
}
}
</script>
you can call this by any event which you know