diff --git a/src/math/big/nat.go b/src/math/big/nat.go
index 6545bc1..121daec 100644
--- a/src/math/big/nat.go
+++ b/src/math/big/nat.go
@@ -2,31 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package big implements multi-precision arithmetic (big numbers).
-// The following numeric types are supported:
-//
-//   Int    signed integers
-//   Rat    rational numbers
-//   Float  floating-point numbers
-//
-// Methods are typically of the form:
-//
-//   func (z *T) Unary(x *T) *T        // z = op x
-//   func (z *T) Binary(x, y *T) *T    // z = x op y
-//   func (x *T) M() T1                // v = x.M()
-//
-// with T one of Int, Rat, or Float. For unary and binary operations, the
-// result is the receiver (usually named z in that case); if it is one of
-// the operands x or y it may be overwritten (and its memory reused).
-// To enable chaining of operations, the result is also returned. Methods
-// returning a result other than *Int, *Rat, or *Float take an operand as
-// the receiver (usually named x in that case).
-//
-package big
+// This file implements unsigned multi-precision integers (natural
+// numbers). They are the building blocks for the implementation
+// of signed integers, rationals, and floating-point numbers.
 
-// This file contains operations on unsigned multi-precision integers.
-// These are the building blocks for the operations on signed integers
-// and rationals.
+package big
 
 import "math/rand"