Bests & Worsts Reviews from Amazon

The product description says "answer on back of card" but in fact the back of the card ALSO has another math problem on it. So these are two-problem cards. That is a big disadvantage when you want to set aside the cards your child has mastered. It is also confusing for children studying on their own. Even for parents it is easy to lose track of which side you were working on with your child. My advice is to buy cards that only have a single problem on them (with the identical problem and its answer on the back), such as those from Trend Enterprises.