To find the sum of an arithmetic series, we can use the formula:

Sn = (n/2)(a + l)

Where:
Sn is the sum of the series,
n is the number of terms in the series,
a is the first term, and
l is the last term.

In this case, the first term (a) is 2, the last term (l) is 100, and we need to find the number of terms (n).

To find the number of terms, we can use the formula:

l = a + (n-1)d

Where:
l is the last term,
a is the first term, and
d is the common difference.

In this case, the common difference (d) is 2, since each term increases by 2.

Using the formula, we can solve for n:

100 = 2 + (n-1)2
100 = 2 + 2n - 2
100 = 2n
n = 100/2
n = 50

Now that we know the number of terms (n), we can find the sum (Sn):

Sn = (n/2)(a + l)
Sn = (50/2)(2 + 100)
Sn = 25(102)
Sn = 2550

Therefore, the sum of the series 2+4+6+8...+94+96+98+100 is 2550.