其它
Each of Basil\textquotesingle s friends added the number of the day and the number of the month of their birthdays and obtained $$35$$. Their birthdays all fall on different days. What is the greatest possible number of friends that Basil has? 
Overseas Competition->Knowledge Point->Counting Modules->Permutations and Combinations->Combinations
Their birthdays could fall on $$5/30$$, $$6/29$$, $$7/28$$, $$8/27$$, $$9/26$$, $$10/25$$, $$11/24$$ and $$12/23$$ to meet the greatest possible number. 