其它
What is the sum of the prime factors of $2010$? (2010 AMC 8 Problems, Question \#14) 
Overseas Competition->Knowledge Point->Number Theory Modules->Prime and Composite Numbers
First, we must find the prime factorization of $2010.2010=2 \cdot 3 \cdot 5 \cdot 67$. We add the factors up to get $(\mathbf{C}) 77$. 