diff --git a/pythonetc/README.md b/pythonetc/README.md
index b2eb723..d4a2791 100644
--- a/pythonetc/README.md
+++ b/pythonetc/README.md
@@ -73,6 +73,7 @@ More:
 1. ./re-compile.md
 1. ./lru-cache.md
 1. ./functools-cache.md
+1. ./tau.md
 
 Out of order:
 
@@ -92,5 +93,3 @@ Unicode module
 String.Template
 String module consts
 Urllib
-Always compile regexp
-Tau vs pi
diff --git a/pythonetc/digits.md b/pythonetc/digits.md
index 9a209a0..b633a08 100644
--- a/pythonetc/digits.md
+++ b/pythonetc/digits.md
@@ -1,4 +1,4 @@
-We used to use Arabic digits to record numbers. However, there are many more numeral systems: Chinese (and Suzhou), Chakma, Persian, Hebrew, and so on. And Python supports them when detecting numbers:
+We use Arabic digits to record numbers. However, there are many more numeral systems: Chinese (and Suzhou), Chakma, Persian, Hebrew, and so on. And Python supports them when detecting numbers:
 
 ```python
 int('٤٢')
diff --git a/pythonetc/tau.md b/pythonetc/tau.md
new file mode 100644
index 0000000..1cff56b
--- /dev/null
+++ b/pythonetc/tau.md
@@ -0,0 +1,15 @@
+Issue with beautiful number [#12345](https://bugs.python.org/issue12345) proposed to add the following constant into stdlib:
+
+```python
+tau = 2*math.pi
+```
+
+It was a contraversal proposal since apparently it's not hard to recreate this constant on your own which will be more explicit, since more people are familiar with π rather than τ. However, the proposal was accepted and tau landed in `math` module in Python 3.6 ([PEP-628](https://www.python.org/dev/peps/pep-0628/)):
+
+```python
+import math
+math.tau
+# 6.283185307179586
+```
+
+There is a long story behind τ which you can read at [tauday.com](https://tauday.com/). Especially good [this numberphile video](http://youtu.be/83ofi_L6eAo).