Batman: Return of the Joker

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Euler problem 20.1

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Find the sum of the digits in the number \displaystyle{100!}.

(reduce #'+
        (map 'list #'digit-char-p
             (write-to-string
              (reduce #'* (loop for i
                                from 1 to 100
                                collect i)))))


CL-USER> 
648

— Me@2024-06-25 08:26:22 PM

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