1 files changed, 31 insertions, 0 deletions
diff --git a/coding-exercises/1/31.rkt b/coding-exercises/1/31.rkt
new file mode 100644
index 0000000..10f52c5
--- /dev/null
+++ b/coding-exercises/1/31.rkt
@@ -0,0 +1,31 @@
+#lang racket
+(require sicp)
+
+(define (id x) x)
+
+(define (factorial n)
+  (product id 1 inc n))
+
+(define (product term a next b)
+  (define (iter result a)
+    (if (> a b)
+      result
+      (iter (* (term a) result) (next a))))
+  (iter 1 a))
+
+(define (even? x)
+  (= (remainder x 2) 0))
+
+(define (pi-product n)
+  (/ (product (lambda (x) 
+                (if (even? x) 
+                  x 
+                  (+ x 1))) 
+              2 inc n)
+     (product (lambda (x)
+                (if (even? x)
+                  (+ x 1)
+                  x))
+              2 inc n)))
+
+(* 1.0 (pi-product 1000))