What is the sum of all the odd integers between 500 and 800?
501 503 505 ...... 795 797 799
We have [799 - 501 ] / 2 + 1 = (298 )/2 + 1 = 149 + 1 = 150 terms
The sum is given by
[ first term + last term ] [number of terms ] / 2
[ 501 + 505 ] [ 150 ] / 2 =
[1300 ] [75 ] =
97500
