Mathematics Education Specialist Math: How to find the number of elements in the union of two sets? By Magic Monk on Thursday, April 11, 2019 In this tutorial we talk about what cardinality of a set means, then we go through how to find the number of elements in the union of two sets, by using the formula |A|+|B|-|A and B|=|A or B|. education mathematics steemiteducation steemstem Previous Post Next Post Related Posts Mathematics Education Vector applications question – Elastic collision, momentum, and kinetic energy Mathematics Education Vectors lesson 21 – Basic vector operations in Geogebra Mathematics Education Vectors lesson 20 – drawing vectors in Geogebra