To find the sum of this series, we first need to determine how many terms there are.

The series starts at -25 and ends at 26, so there are 52 terms in total.

Now, we can use the formula for the sum of an arithmetic series:

S = n/2 * (a_1 + a_n)

where S is the sum of the series, n is the number of terms, a_1 is the first term, and a_n is the last term.

Plugging in the values we have:

S = 52/2 (-25 + 26)
S = 26 1
S = 26

Therefore, the sum of the series is 26.