Mental Math Cards Games & Tips funktioniert nicht

Mental Math Cards is designed to help people of all ages and skill levels improve their arithmetic abilities through easy to remember (and use) tips, practice question sets, and an addictive game.  Given that flexibility, Mental Math Cards is as appropriate for use by beginning students as it is for college graduates looking to sharpen there skills for quantitative interviews and to impress friends & colleagues.  Mental Math Cards provides step by step instructions on how to approach solving all of the problems it shows - for all operations and difficulty levels.  Mental Math Cards supports all four of the major arithmetic operations - as well as a mixed operations mode that randomly shows all types of problems.  It includes a lot of well written instructions on how to master the tougher problems". ***** - Keep it up! - "This game is a fun way for grown ups to keep up on their math skills.  Mental Math Cards provides additional features using a subscription model - that includes a 3 day trial period.  Unlike many other math apps, advanced problems are also supported to keep things challenging as your skills improve.  Professionals: Impress colleagues, family, and friends with lightening fast and accurate mental math skills.  Mental Math Cards supports 1 by 1, 2 by 1, 2 by 2, and 3 by 3 digit problems.  Mental Math Cards is fully integrated with Game Center - providing both Leaderboards and Achievements.  Want to improve your math skills with out having to memorize a hundred tricks?  The Game Center features allow you to test your skills against the rest of the world and to share your scores and accomplishments with friends.  Students: Prepare for the math sections of the PSAT, SAT, ACT, GRE, GMAT, and MCAT, as well as for regular school tests.  Impress interviewers during job interviews that have quantitative component by solving problems with out needing a pencil and paper.  Each difficulty level for each operation type is carefully thought out to build on the skills mastered in previous levels.  For instance, hard multiplication problems are shown to be solvable by breaking problems down into medium and easy level problems.