diff --git a/sicp-ex-1.23.rkt b/sicp-ex-1.23.rkt
new file mode 100644
index 0000000..3275568
--- /dev/null
+++ b/sicp-ex-1.23.rkt
@@ -0,0 +1,21 @@
+(define (square n)
+  (* n n))
+
+(define (smallest-divisor n)
+  (find-divisor n 2))
+
+(define (find-divisor n test-divisor)
+  (define (next iterator)
+    (if (= iterator 2) 3 (+ iterator 2)))
+  
+  (cond ((> (square test-divisor) n) n)
+        ((divides? test-divisor n) test-divisor)
+        (else (find-divisor n (next test-divisor)))))
+; find-divisor
+
+(define (divides? a b)
+  (= (remainder b a) 0))
+
+(smallest-divisor 199)
+(smallest-divisor 1999)
+(smallest-divisor 19999)