display total price on product info page

Hi,

Not sure if I've picked the right spot to post this question, but here goes:

I am setting up my products to show their unit price, with a minimum quantity of 50. I'd like to show the total price underneath the unit price on the product info page.

I'm not a PHP expert, but I can read and understand a small amount. I have tried the following, but it doesn't work because the currency symbol is in the way.

	
$totalprice = zen_get_products_display_price((int)$_GET['products_id'])*50; 
	echo '<p class="biggerText">50 for ' . $totalprice . '</p>'; 

Can anyone help me with how to strip the currency symbol, multiply the resulting number by 50, and then add the currency symbol back in?