GreenWoody is an app aimed at kids between ages 6 to 12, for practicing mental mathematics. Mental addition, subtraction, multiplication and addition can be practiced. The ranges of numbers that will be used in the problems to be solved can be specified. If desired, practice can be done with a timer in the screen as well. A total score is calculated as the student practices, with correct answers shown in case a problem is not answered correctly. A new practice session can be started at any time by resetting the practice session.The name GreenWoody refers to the tree of knowledge that children and people eat from to gain learning and understanding. One of its fruits is math and mental calculation.