   /// - Parameters:
   ///   - value: The value to convert to a string.
   ///   - radix: The base to use for the string representation. `radix` must be
-  ///     at least 2 and at most 36.
+  ///     at least 2 and at most 36. The default is 10.
   ///   - uppercase: Pass `true` to use uppercase letters to represent numerals
   ///     greater than 9, or `false` to use lowercase letters. The default is
   ///     `false`.
   public init<T : UnsignedInteger>(
-    _ value: T, radix: Int, uppercase: Bool = false
+    _ value: T, radix: Int = 10, uppercase: Bool = false
   ) {
     _precondition(radix > 1, "Radix must be greater than 1")
     self = _uint64ToString(


// Conversions to string from other types.
extension String {

  // FIXME: can't just use a default arg for radix below; instead we
  // need these single-arg overloads <rdar://problem/17775455>
  
  /// Creates a string representing the given value in base 10.
  ///
  /// The following example converts the maximal `Int` value to a string and
  /// prints its length:

  ///     let max = String(Int.max)
  ///     print("\(max) has \(max.utf16.count) digits.")
  ///     // Prints "9223372036854775807 has 19 digits."
  ///
  /// Numerals greater than 9 are represented as Roman letters. These letters
  /// start with `"A"` if `uppercase` is `true`; otherwise, with `"a"`.
