These are mental math worksheets for 3rd, 4th, 5th and 6th Grade. These 16 crossnumber puzzles are flexible math center activities, warm ups, back to school review activities, end of year review activities, test prep, bell ringers, early finishers, and homework activities. Great for last minute math sub lessons and for differentiation, or teachers who move between different grades. This BUNDLE includes a packet of 8 puzzles worksheets originally created for Third and Fourth Grade, and another pa