# Alternating series test

In mathematical analysis, the **alternating series test** is the method used to show that an alternating series is convergent when its terms (1) decrease in absolute value, and (2) approach zero in the limit.
The test was used by Gottfried Leibniz and is sometimes known as **Leibniz's test**, **Leibniz's rule**, or the **Leibniz criterion**. The test is only sufficient, not necessary, so some convergent alternating series may fail the first part of the test.

Part of a series of articles about |

Calculus |
---|