Smokeybear00 wrote:

If n is the sum of the first 40 positive integers, what is the greatest prime factor of n?

A. 29

B. 37

C. 41

D. 17

E. 19

Nice question.

Sum of consecutive integers =

\(\frac{(First Term + Last Term)*(n)}{2}\), where n = number of terms

The first term is 1. The last term is 40.

Using the formula above, the sum is

\(\frac{(1 + 40)*(40)}{2}\)

=

(41)(40) / 2

Stop there. 41 is a factor of the sum, and 41 is prime.

Answer C

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