What is the greatest prime factor of 1+2+3+。。。+106? Choose one.
A) 131	B) 127	C) 99	D) 101	E) 107
find the sum from direct formula = n(n+1)/2 = 106(106+1)/2 = 53*107...   107 is a PRIME number, so ans is 107..   101 is the answer
<result>D</result>
What is the greatest prime factor of 1+2+3+。。。+106?