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    OlympiadEasyCombinatorics7–9

    Pattern Recognition

    Reconhecimento de Padrões

    Find the last digit of 720247^{2024}.

    The last digits of the powers of 7 repeat. Work out enough of them for the cycle to show itself.

    Solution

    Step 1 of 5

    1. 1.Last digits of powers of 7: 7, 9, 3, 1, 7, 9, 3, 1, ...