This is a simple math drilling device / calculator.  It consists of 8 levels of each of the following area -- addition, subtraction, multiplication, division, decimals, fractions and percentages.  The levels progress rather slowly from simple (1+3) to algebraic thinking (? + 13=42).  I like that the multiplication allows you to select the times table that you will be working with.  You can use the sound, or not and there is a red light or green light to indicate whether you have reached the correct answer.