Cards
Set completion calculator
How many packs to finish a set, given duplicates? The coupon-collector answer.
The formula
With N unique cards and k cards per pack, the expected number of packs to collect all N (coupon collector) is (N / k) × H(N), where H(N) is the harmonic number. That assumes every card is equally likely and packs are independent. Real sets have short prints and collation, so treat this as a floor, not a promise.