what is the sum of all even numbers between 1 and 1000

There are 500 even numbers from 1 to 1000 starting with 2 and ending with 998. The sequence of even numbers is an arithmetic sequence with a common difference of 2. Using the equation for the arithmetic series,

S = (a1 + an) (n/2)

and substituting,

S = (2 + 998) (500/2)

we get,

S = 250,000

Therefore, the sum of all even numbers between 1 and 1000 is 250,000.