Hash key on Dell Mobile Keyboard

Hi,

I'm on a Dell Venue pro 11 and I'm using an American Dell mobile keyboard. I set it with the English layout on Windows (> "English United Kingdom > United Kingdom Keyboard").

Actually not all the typed keys do correspond to the symbols printed on it (i.e. to type the @ I have to push the " and vice versa).

In any case I cannot find the buttons I have to press to type the Hash (this symbol: #) with the physical keyboard. There is a button with the #, but while pushing it I obtain £.

I'm sure there is such a combination to obtain #, because once I obtained it in a completely random way, accidentally.

Can you help me to find the # key and possibly to understand why some letters I type on the keyboard don't correspond to those which appear on the screen?

I often switch from the English to the Italian layout and vice versa while using the virtual keyboard, sometimes I did it with the mobile keyboard inserted, I wonder if the anomalies may depend on this...

Thank you.