YinYu is a wonderful, fascinating mathematical game for children of ages 9 years old or over. This app is especailly targeted to STEM programs in middle school and high school.YinYu uses PEMDAS to evaluate the polynomial expressions so school children over 9 years old play a game while learning how to evaluate and build PEMDAS algebraic expressions. PEMDAS algebraic expressions are used in mathematics and in computer software evaluations.We have a YinYu Worldwide Leader Board for keeping track of your scores.Try to be Ranked World Number #1!!There are three major steps with 17 levels in each step.Step 1 - Levels 1 – 17 (Start Levels):The game will randomly select numbers from 1 through 20. You must solve for the given answer using the three numbers (operands) and two operators. Every time you solve a question you go up to the next level and gain higher and higher scores to post to the Leader Board!! Step 2 - Levels 17 -34 (Harder Levels)The game will randomly select numbers from 1 through 100. You must solve for the given answer using four numbers and three different operators. Base score points double.Step 3 - Levels 34 and up (Hardest Levels):The game will randomly select numbers from 1 through 100. You must solve for the given answer using all 5 numbers and all 4 operators. Base score points triple.Score points are earned by the remaining time on the timer, if time expires and you can solve the puzzle and base points are earned.The Leader Board is a WorldWide, Global Leader Board and is stored in the Google Play Services cloud. Try to be Ranked World Number #1!!