diff --git a/Labs/03.rkt b/Labs/03.rkt
new file mode 100644
index 0000000..1ab20bb
--- /dev/null
+++ b/Labs/03.rkt
@@ -0,0 +1,42 @@
+#lang plait
+(define-type Nat
+  [Z]
+  [S (pred : Nat)])
+  
+(define (plus nat1 nat2)
+  (type-case Nat nat1
+    [(Z) nat2]
+    [(S pred) (S (plus pred nat2))]))
+
+(define (compare nat1 nat2)
+  (type-case Nat nat1
+    [(Z)
+     (type-case Nat nat2
+       [(Z) 'equal]
+       [(S pred) 'less])]
+    [(S pred1)
+     (type-case Nat nat2
+       [(Z) 'greater]
+       [(S pred2) (compare pred1 pred2)])]))
+
+(define (times nat1 nat2)
+  (type-case Nat nat1
+    [(Z) (Z)]
+    [(S pred)
+     (type-case Nat nat2
+       [(Z) (Z)]
+       [(S pred2) (plus nat2 (times pred nat2))])]))
+
+(test (plus (Z) (S (Z))) (S (Z)))
+(test (plus (S (Z)) (Z)) (S (Z)))
+(test (compare (Z) (Z)) 'equal)
+(test (compare (Z) (S (Z))) 'less)
+(test (compare (S (Z)) (Z)) 'greater)
+(test (compare (S (S (Z))) (S (Z))) 'greater)
+(test (times (Z) (Z)) (Z))
+(test (times (Z) (S (Z))) (Z))
+(test (times (S (Z)) (Z)) (Z))
+(test (times (S (S (Z))) (S (Z))) (S (S (Z)))) ; 2 x 1
+(test (times (S (Z)) (S (S (Z)))) (S (S (Z)))) ; 1 x 2
+(test (times (S (Z)) (S (Z))) (S (Z))) ; 1 x 1
+(test (times (S (S (Z))) (S (S (Z)))) (S (S (S (S (Z)))))) ; 2 x 2
\ No newline at end of file