InterviewSolution
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InterviewSolution
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What is the last digit of `3^(3^(4n)) +1`, where n is a natural number?A. 2B. 7C. 8D. None of these |
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Answer» Correct Answer - D In `3^(n)`, last digit is 3, if n=1,9 if n=2,7 if n=3 and 1 if n=4 and it is repeated after than Given expression is `3^(3^(4n))+1` Let `x=3^(3^(4n))+1=3^(8"In")+1` `rArr" "x=3^(80n).3^(n)+1` Last digit of x will be decided by `3^(n)" since "3^(80n)` has power multiple of 4. If n=1 last digit is 3+1=4 n=2 last digit is `3^(2)+1=9+1=10` So, last digit is zero. n=3 last digit is `3^(3)+1=27+1=28` last digit is 8. If n=4 last digit is `3^(4)+1=81+1=82` last digit is 2. So, there is no definite value of last digit. |
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