diff --git a/3/euler3.rkt b/3/euler3.rkt
new file mode 100644
index 0000000..55e5fbf
--- /dev/null
+++ b/3/euler3.rkt
@@ -0,0 +1,14 @@
+#lang racket
+
+(require math/number-theory)
+
+(define (primes x) (filter prime? (range 2 (sqrt x))))
+
+(define (primefactors x primes)
+  (if (prime? x)
+      (list x)
+      (if (zero? (remainder x (car primes)))
+          (cons (car primes) (primefactors (quotient x (car primes)) primes))
+          (primefactors x (cdr primes)))))
+
+(apply max (primefactors 600851475143 (primes 600851475143)))
\ No newline at end of file