This product includes 12 cards and 1 recording sheet (copy front to back). There are 6 plain number subtraction problems and 6 subtraction story problems. To use as a math center, copy the cards onto card stock and laminate then place randomly around the room. Students move around the room locating each card and writing it in the matching box on their recording sheet. When they've answered all the questions they color each box yellow or green depending on whether the question required regrouping or not. My second graders LOVE this activity and most of them can complete it in about 30 minutes.