diff --git a/Doc/library/timeit.rst b/Doc/library/timeit.rst
index ef7a4e4..46fa62c 100644
--- a/Doc/library/timeit.rst
+++ b/Doc/library/timeit.rst
@@ -251,7 +251,8 @@
 similarly.
 
 If :option:`-n` is not given, a suitable number of loops is calculated by trying
-successive powers of 10 until the total time is at least 0.2 seconds.
+increasing numbers from the sequence 1, 2, 5, 10, 20, 50, ... until the total
+time is at least 0.2 seconds.
 
 :func:`default_timer` measurements can be affected by other programs running on
 the same machine, so the best thing to do when accurate timing is necessary is
diff --git a/Lib/timeit.py b/Lib/timeit.py
index c0362bc..6c3ec01 100755
--- a/Lib/timeit.py
+++ b/Lib/timeit.py
@@ -29,7 +29,8 @@
 treated similarly.
 
 If -n is not given, a suitable number of loops is calculated by trying
-successive powers of 10 until the total time is at least 0.2 seconds.
+increasing numbers from the sequence 1, 2, 5, 10, 20, 50, ... until the
+total time is at least 0.2 seconds.
 
 Note: there is a certain baseline overhead associated with executing a
 pass statement.  It differs between versions.  The code here doesn't try