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

1 Answer
Massimiliano
Mar 30, 2015

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.

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