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# greatest prime divisor

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Find the greatest prime divisor of the sum of the arithmetic sequence

1+2+3+.......+80+81+82+83

Jan 27, 2021

#1
+165
+2

That sum is equal to $$\frac{83(84)}{2}=83(42)$$. Since 83 is prime, and it is greater than 42, it must be the biggest prime divisor. Therefore, 83 is the answer.

Jan 27, 2021

#1
+165
+2

That sum is equal to $$\frac{83(84)}{2}=83(42)$$. Since 83 is prime, and it is greater than 42, it must be the biggest prime divisor. Therefore, 83 is the answer.

textot Jan 27, 2021
#2
+116126
+1

Very astute, textot   !!!!

CPhill  Jan 27, 2021