Add 1.16

sicp-ex-1.16

@@ -0,0 +1,19 @@
+; UNFINISHED
+(define (sqr n)
+  (* n n))
+
+(define (fast-ext-iter number power product)
+  (cond ((= power 0) product)
+        ((even? power) (fast-ext-iter number
+                                      (/ power 2)
+                                      (if (= product 1)
+                                          (sqr number)
+                                          (sqr product))))
+        (else (fast-ext-iter number
+                             (- power 1)
+                             (* power product)))))
+
+(define (fast-ext number power)
+  (fast-ext-iter number power 1))
+
+(fast-ext 2 8)