Discussion

Find the unit digit of the expression \(11^1 + 12^2 + 13^3 + 14^4 + 15^5 + 16^6\).

Answer: B

We only need to find the unit digit of each term and add them.

Unit digit of \(11^1\) is 1.

Unit digit of \(12^2\) is the unit digit of \(2^2\), which is 4.

Unit digit of \(13^3\) is the unit digit of \(3^3=27\), which is 7.

Unit digit of \(14^4\) is the unit digit of \(4^4=256\), which is 6.

Unit digit of \(15^5\) is 5.

Unit digit of \(16^6\) is 6.

Sum of unit digits = \(1+4+7+6+5+6 = 29\).

The unit digit of the final expression is the unit digit of 29, which is 9.

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