Fangrui Product Details Digital Education Seal Roller: This Mathematical Roller Seal Is Very Convenient Compared To Writing Each Mathematical Equation Every Time. Using A Double Headed Scroll Wheel, You Can Rotate The Numbers To Obtain Different Combinations Of Equations To Solve, Print Clearly, And Do Not Fade. Double Headed Design: Add/multiply And Subtract/divide On Both Sides, You Can Choose One Or The Other. [different Equation Combinations] You Can Rotate The Knob Of The Scroll Wheel To Change The Number To Obtain Different Combinations. This Math Roller Is Suitable For Student Practice, Parent Guidance, Teacher Instruction, Stationery, And School Supplies. Develop Mathematical Logic Skills: Without Parental Help, Your Child Can Develop Different Mathematical Equations And Then Solve Them. Enjoy Math And Practice Logical Thinking Skills. If You Want Something Simple And Interesting To Help Your Child Learn Simple Math, Then This Is A Good Choice. Convenient : This Teaching Seal Set Is Filled In Advance. When Th