DIGITAL TEACHING STAMP ROLLER: Our math stamps come in 4 styles, addition, subtraction, multiplication and division. Scroll gently, math problems will appear. It prints math problems within 100 quickly. REUSABLE MATERIALS: The math roller stamp is made of PVC material and uses cuts to ensure a clear impression every time. Dries quickly without fading. With oil-based ink, no acid or lignin, for school or home use. ADJUSTABLE DESIGN: The Math Practice Number Rolling Stamp has 10 different ways to queue, and you can change the calculation questions with just the turn of a button. Say goodbye to handwritten addition and subtraction math problems, and use the seal to save you more time. PORTABLE SIZE: The Roller Digital Teaching Stamp is small and exquisite, and comes with a storage box for carry. When the ink is used up, you can fill it on the roller side. MAKE LEARNING MATH FUN: Math Roller Stamp can develop your child or student's logical calculation ability and improve the speed and accuracy of oral calculation. YOUBLEK teaching stamps make great gifts compatible with Birthdays, Christmas, Halloween, Thanksgiving and New Years.