Current time:0:00Total duration:7:47

0 energy points

# Arithmetic series formula

The sum of the first n terms in an arithmetic sequence is (n/2)⋅(a₁+aₙ). It is called the

*. Learn more about it here. Created by Sal Khan.***arithmetic series formula**If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains ***.kastatic.org** and ***.kasandbox.org** are unblocked.

Main content
# Arithmetic series formula

Current time:0:00Total duration:7:47

0 energy points

The sum of the first n terms in an arithmetic sequence is (n/2)⋅(a₁+aₙ). It is called the **arithmetic series formula**. Learn more about it here. Created by Sal Khan.