It's mathematically correct everyone will be doing in a couple of years (I can confirm from they future that everyone does now checkout 50 double 9 double 16. 2 years later)
I don't think the math is the problem technically as it's simple addition and subtraction. the problem is to do it in a split second and whilst keeping your concentration
Jesus love you, he died on the cross for you, accept him as your lord and savior he can change everything. For God so loved the world that he gave his only son, so that everyone who believes in him may not perish but may have eternal life" (Jn 3:16" But you must repent too. From that time Jesus went about preaching and saying, Let your hearts be turned from sin, for the kingdom of heaven is near. (Matthew 4:17)~
A *LEG* of darts... Not even a *SET.* That's what really used to annoy me about these competitions they ran for those during the Lakeside championship. Fob off.