What is the greatest prime factor of 1+2+3+。。。+70?  Choose the correct choice from the following answers:
A) 71  B) 69  C) 31  D) 59  E) 101
find the sum from direct formula = n(n+1)/2 = 70(70+1)/2 = 35*71...   71 is a PRIME number, so ans is 71..   71 is the answer
<result>A</result>
What is the greatest prime factor of 1+2+3+。。。+70?