Quandaries
and Queries 

the level of the question: Precalculus (grade 10) Question: If 2 to the power of 31921 is multiplied out, what will be the units digit? Thank you! 

Hi, Start to calculate powers of 2 and watch the units digit
Do you see what's happening? The units digits column is repeating in cycles of length 4, If you continue this list for 31921 rows how many cycles of length 4 will there be? How many more rows are there after that? What is the units digit in the 31921^{th} row? Cheers,Penny 

