What is the greatest prime factor of 1+2+3+。。。+22?  Select the correct option
A) 17 B) 29 C) 23 D) 37 E) 11
find the sum from direct formula = n(n+1)/2 = 22(22+1)/2 = 11*23...   23 is a PRIME number, so ans is 23..   23 is the answer
<result>C</result>
What is the greatest prime factor of 1+2+3+。。。+22?