First To Fifty
Riddle: Zack invented a game for him and his friend Dan to play. They would take turns saying numbers between one and 10. The next player would have to say a number that is greater than the previous one by a number between one and 10. The first player to say 50 would be the winner. Zack decides to let Dan start. How can Dan win?
Answer: If Dan wants to say 50, then he needs Zack to say a number between 40 and 49, so right before 50, Dan needs to say 39. If he wants to say 39, then Zack needs to say a number between 29 and 38, so right before 39, Dan needs to say 28. If Dan wants to say 28, Zack has to say a number between 18 and 27, so right before 28, Dan has to say 17. And if he wants to say 17, he has to let Zack say a number between 7 and 16, so right before 17, Dan has to say 6. In order to win, Dan needs to say 6, then 17, then 28, then 39, and finally 50.
Source: https://www.riddles.com/index.php/11342
