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Units of Seven

Problem Statement
Find the units digit of 7189. Determine a general rule for finding the units digit of 7n,where n is any whole number.

Problem setup

What number is in the ones place when I evaluate 7189 ?


Plans to Solve/Investigate the Problem

I plan to use a spreadsheet using  7^nth and look for a pattern.


Investigation/Exploration of the Problem

I noticed that the units digits form a pattern of 1, 7, 9, 3. This is a four digit repeating pattern. I then divided 189 by 4, I had a remainder of 1. Thus I thought 1 would be the units digit of 7189.  After class discussion I realized that 7^0 =1 is not part of the pattern. Thus the pattern is 7, 9, 3, 1. The units digit will be a 7.


Author & Contact
Dottie Mitcham

Link(s) to resources, references, lesson plans, and/or other materials
Link 1
Link 2


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