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

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

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

In this case, the first term (a) is 6, 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 d is the common difference. In this case, the common difference is 2.

100 = 6 + (n-1)2
100 = 6 + 2n - 2
100 - 6 + 2 = 2n
96 = 2n
n = 48

Now we can substitute the values into the sum formula:

Sn = (n/2)(a + l)
Sn = (48/2)(6 + 100)
Sn = 24(106)
Sn = 2544

Therefore, the sum of the series 6+8+10+...+100 is 2544.