First choose your skill to practice (addition, subtraction, multiplication, or division). Then, choose the numbers you want to practice. Finally, indicate whether or not to allow negative numbers. For example, if you want to practice adding 1, 2, and 3, click on the 1 bubble, the 2 bubble, and the 3 bubble. Finally, set the countdown to however many seconds you want and see how many problems you can correctly answer, or, set an attainment goal, and see how long it takes you to reach your goal! If you reach your goal, you can print out your very own certificate of achievement.