Quantity Issue When Using Woocommerce

Hi Everyone- I am having a bit of an issue with my site and I am hoping someone can help me fix it, it’s probably an obvious solution but I just can’t seem to figure it out. I am using gravityforms for my order page on my site asapletters.com. When I input the desired quantity the total price is updated correctly, however when I select add to cart it is adding one extra to the total. My product is $0.64/ea so if I add 100, my total is $64.00 as displayed on the order page but when I go to my shopping cart the total is showing $64.64. Can anyone please help? Thanks in advance!