Math

My local supermarket runs a campaign where you can collect stickers for a photo album 📔 with historic pictures of our pitoresk town. For every 10 euros you get a package of 4 stickers and in total there are 229 unique stickers. My question is: How many stickers including doubles do you need to get a full album? 💁 This is known as the Coupon collector’s problem (a variant of the birthday problem)....