We have a series where the sum of any 7 consecutive terms is negative and the sum of any 11 consecutive terms is positive. What is the maximum number of terms in this series?
The number of terms can't be 77 or greater, for then each of the 7 sums 1-7,8-14,...,71-77 are negative while the 11 sums 1-11,12-22,...,67-77 are positive.
quick upper limit
