What better way to practice subtraction facts that with a product that incorporates the use of technology using QR codes. Students love using QR codes and this allows for independent learning, more student engagement, and fun. Print on card stock, laminate, and students can write their equations in a spiral or on the answer sheet provided. There are 28 cards . Use a QR code reader,(ipad, android phone, iphone). You can get a QR code reader app free through your play store. The QR codes are optional. This product has 28 cards for students to practice subtracting from 12, 13, 14, 15, 16, 17 & 18.