diff --git a/types/src/number/mod.rs b/types/src/number/mod.rs
index 16d8f5e..9265810 100644
--- a/types/src/number/mod.rs
+++ b/types/src/number/mod.rs
@@ -20,10 +20,7 @@ use super::value::*;
 type Int = i64;
 type Flt = f64;
 
-trait Number: Debug + IsBool + IsChar + IsNumber + Value {
-    /// Convert a Number to the next lowest type in Scheme's number pyramid, if possible.
-    fn convert_down(&self) -> Option<Box<Number>>;
-}
+trait Number: Debug + IsBool + IsChar + IsNumber + Value { }
 
 trait IsExact {
     /// Should return `true` if this Number is represented exactly. This should be an inverse of