The (E)-(Z) System for Designating Alkene Diastereomers

A system that works in all cases is based on the priorities of groups in the Cahn-Ingold-Prelog convention. This system , called the (E)-(Z) system applies to alkene diastereomers of all types.
How to use (E)-(Z) system
1. Examine the two groups attached to one carbon atom of the double bond and decide which has higher priority.
2. Repeat that operation on the other carbon.
3. Compare the groups of higher priority on one carbon atom with the group of higher priority on the other carbon atom. If the two groups of higher priority are on the same side of the double bond, the alkene is designated (Z). If the two groups of higher priority are on opposite sides of the double bond, the alkene is designated (E).