What is the sum of the first 10, consecutive even integers?

Question: What is the sum of the first 10, consecutive even integers?

Solution:
First 10 consecutive even integers are,
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
This is an arithmetic series.

Now, First term, a = 2
Last term, l = 20
And number of terms, n = 10

We know,
Sum, S_n = n(a + l)/2
= 10(2 + 20)/2
= 10 × 11
= 110