Competition problem — Number theory

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Number theory Difficulty 3.9 AMC 10/12 Find the answer South Africa

The last digit of $2011 \times 2013 \times 2015 - 2010 \times 2012 \times 2014$ is

Pick one

Solution

The last digit of $2011 \times 2013 \times 2015$ is a five, and the last digit of $2010 \times 2012 \times 2014$ is zero, so the last digit of the difference will be $5 - 0 = 5$ .

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