It is a calculation iteration problem collection of watches for the second grade. Rather than buy a drill, rather than buy a collection of problems, Repetitive practice a free app! Calculation is determined by the amount of repetition!
By performing the repeated calculation, let's improve the academic achievement.
This is the format to choose the answer to the problem from the 4-choice.
Problems are questions at random. 20 questions at a time will be questions in succession.