Rule of Sum

Pronunciation: /rul ʌv sʌm/ Explain
The rule of sum is a rule in probability that states when selecting from two sets of events that can not both happen, the number of possibilities of each of the events is added together to get the total number of possible events. Example: Andrea wants dessert. She can stay home and choose from apples or kiwi. Or she can go to the store and buy bananas. There are 2 choices at home and 1 at the store, making a total of 2 + 1 = 3 choices.


  1. McAdams, David E.. All Math Words Dictionary, rule of sum. 2nd Classroom edition 20150108-4799968. pg 173. Life is a Story Problem LLC. January 8, 2015. Buy the book

Cite this article as:

McAdams, David E. Rule of Sum. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC.

Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
5/5/2011: Initial version. (McAdams, David E.)

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