In all honesty, it depends on the size of the PVA bag, but assuming a bag approximately 80mm x 140mm, I'd guess at 10-15 (You have to bear in mind that 400g is the packaged weight and (As far as I know) you get about 375g of stick mix delivered).
Personally, I'd be adding hemp / pigeon conditioner / maize to the mix so I'd double the amount of bags.