[regex] Simple regular expression for a decimal with a precision of 2

For numbers that don't have a thousands separator, I like this simple, compact regex:

\d+(\.\d{2})?|\.\d{2}

or, to not be limited to a precision of 2:

\d+(\.\d*)?|\.\d+

The latter matches
1
100
100.
100.74
100.7
0.7
.7
.72

And it doesn't match empty string (like \d*.?\d* would)