Thanks to weeman for the info below.
To find out what your mobile number is:
1) Open a new blank text message
2) Type in "number" without quotes (")
3) Type 2020 as recipient
5) Receive a text message back with your number in it.
So in essence as well as sending "settings" to 2020 you can now send ""number"
You could also add that it's free to text 2020.