Return Part of a text field

I have a table with a field named "swNotes". The field type is ntext. The
field can contain a variety of data. What I need to do is pull out just one
particular piece. Here is an example of 4 different rows of data in the
"swNotes" field:

--> Color = Green <-- --> Number = 1 <-- --> Notes = Today is Thursday. <--
--> Number = 25 <-- --> Notes = Hello <--
--> Weather = Hot <-- --> Notes = I need help. <-- --> Number = 567 <--
--> Color = Green <-- --> Notes = No number in this row. <--

My goal is to retrieve "Number = xxx".
So my returned data should be:

Number = 1
Number = 25
Number = 567
Null

Since "Number = " is not in the same position each time substring does not
work. And in some cases the "Number = xxx" is not provided.

Using Query Analyzer how can I complete this task?

Thanks.
.