+510 Find the greatest prime divisor of the value of the arithmetic series
1 + 2 + 3 + \dots + 135 + 136 + 137 + 138 + 139 + 140.
+1938 So for this problem, let's use the arithmetic series formula.
We find the sum is \(\frac{(140+1)(70)}{2}\), which is \(141*35.\) Now that we have a factorization, we can easily find the greatest prime divisor.
The prime factorization is \(3*5*7*47\), so the greatest prime divisor is 47.
Thanks! :)
