Project Euler

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# [[Problem 3]]

```scheme

#!r6rs

#!chezscheme

(import (chezscheme))

(define answer-3

  (let* ((n 600851475143)

         (check-max (isqrt n)))

    (let loop ((current 3) (rest n) (max-prime 1))

      (cond

        [(< check-max current) max-prime]

        [(zero? (mod rest current))

         (loop current (div rest current) current)]

        [else (loop (+ current 2) rest max-prime)]))))

(printf "3: ~D~%" answer-3)

```