Category:  Mobile applications and art Project name: "Math joy" Author:  Boyan Paskalev Country:  Bulgaria URL: https://play.google.com/apps/publish/?dev_acc=12675902005363517756#MarketListingPlace:p=com.bp.mathr Registration date: 19.08.2015 Description: Keep your mind healthy, test your mental math and exercise your brain once a day. This is the best math trainer.