Arithmetic Sequence Calculator

About this calculator

This calculator finds the nth term of an arithmetic sequence (aₙ = a₁ + (n − 1)d, where d is the common difference added at every step) and the sum of the sequence up to that term, from just the first term and the common difference. An arithmetic sequence is any list of numbers where each term differs from the last by the same fixed amount, whether that amount is positive, negative or a fraction.

Students use it to check sequence and series homework without writing out every term by hand, which becomes impractical once n gets into the hundreds or thousands. The same math underlies real patterns like a savings plan that adds a fixed amount each period, a venue's seating where each row has a fixed number more seats than the last, or any process that increases or decreases by a constant step.