What is the last digit in the number #7^(7^(7^(7^(7^(7^7)))))# ?

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Answer 1 · 2015-03-30T19:56:38

The answer is: #7#.

This is because:

#7^7=a# it's a number whose last digit is #3#.

#a^7=b# it's a number whose last digit is #7#.

#b^7=c# it's a number whose last digit is #3#.

#c^7=d# it's a number whose last digit is #7#.

#d^7=e# it's a number whose last digit is #3#.

#e^7=f# it's a number whose last digit is #7#.