This PRINTABLE set of 50 cards allows your students to practice basic math facts by looking at combinations of numbers. Combinations include sums of 4 to 16. Mystery numbers may be an addend or the sum. Use these cards many different ways from small group practice, independent centers or stations, or even 5 minutes a day before lunch, recess, or dismissal. Students can never have enough practice in seeing math facts presented in multiple ways. Watch your students speed increase with repetition. PDF version easily printed. Challenging for younger students and a great way to strengthen or use as remediation with older students.