Javascript maths problem

[slpixe]

Hey all

I got less than 3 hours to get this sorted >.<!!

I need to be able to calculate this in javascript and its going to require some maths formula I can't seam to land on no matter how many times I play around with it.

Its to work out a parcel price
and this parts based on weight

Less than 500g's is £1.65, Done
Less than 1kg is £3.00, Done

When above 1kg, £1 for each additional 500g!

I have been trying 3 different codes, my last one is the closest, but I been tweaking it loads, and can't get it to land on correct answer.

/*if (valu3>999)
{price=3;
valu3-1000;
valu3/500;}*/
/*
if (valu3>999)
{price=valu3+499/500}*/

if (valu3>999)
{price=valu3-1000/500}


alert(price);}

Valu3 = weight
price = output

I hope someone's really good at maths that they can work out figures to be able to calculate the price depending on this sort of stuff.

Thanks in advance

[VPmase]

Give me a min or so and I'll help.

Edit- Here is my scripts. Works perfectly for every 500g

<form name="price">
<input type="text" name="wp" id="wp" onkeyup="getPrice();" />G<br />
<input type="text" readonly="readonly" name="price" id="price" />
</form>
<script>
function getPrice(){
	var price;
	var wpp;
	wpp = parseInt(document.price.wp.value);
	if(wpp >= 500){
		var multiplyer = Math.floor(wpp/500);
		var extraprice = 1;
		var origcost = 0;
		var extracost = 0;
		switch(multiplyer){
			case 1:
				//£1.65
				origcost = 1.65;
			break;
			case 2:
				//£3.00;
				origcost = 3.00;
			break;
			default:
				origcost = 3.00;
				extracost = (multiplyer - 2) * extraprice;
			break;
		}
		document.price.price.value = "£" + (origcost + extracost);
	} else {
		document.price.price.value = "";
	}
}
</script>

[slpixe]

Oh wow thanks so much!
that's insanely good!

you saved my life XD
+Rep for you =D

[VPmase]

You're welcome and thank you for the compliment

*Closed*