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Math Help - Finding last two digits of a large number

  1. #1
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    Finding last two digits of a large number

    Hello, I have a problem solving this :

    23^(24^25)

    I am supposed to find the last two digits of this number. I know I have to find the remainder after the modulo 100 operation but all together I'm lost. Thank you for help.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by merlin1x1 View Post
    Hello, I have a problem solving this :

    23^(24^25)

    I am supposed to find the last two digits of this number. I know I have to find the remainder after the modulo 100 operation but all together I'm lost. Thank you for help.
    First find y(1)=23^24 mod 10. Now construct the sequence:

    y(n)=y(n-1)^24 mod 10

    so y(n)=23^(24^n) mod 10

    CB
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