diff --git a/types/src/value.rs b/types/src/value.rs
index e40827e..1cc93fe 100644
--- a/types/src/value.rs
+++ b/types/src/value.rs
@@ -23,11 +23,11 @@ pub trait IsNumber {
     /// Should return `true` if this Value is a number type.
     fn is_number(&self) -> bool { self.is_complex() || self.is_real() || self.is_rational() || self.is_integer() }
     /// Should return `true` if this Value is a complex number type.
-    fn is_complex(&self) -> bool { false }
+    fn is_complex(&self) -> bool { self.is_real() }
     /// Should return `true` if this Value is a real number type.
-    fn is_real(&self) -> bool { false }
+    fn is_real(&self) -> bool { self.is_rational() }
     /// Should return `true` if this Value is a rational number type.
-    fn is_rational(&self) -> bool { false }
+    fn is_rational(&self) -> bool { self.is_integer() }
     /// Should return `true` if this Value is a integer number type.
     fn is_integer(&self) -> bool { false }
 }