How can I type a backslash with no backslash key?

I have found out that Alt Gr+- gives \.

Press the alt key to the right of the space bar (alt gr), and the key above the enter key (which should typically be hash on a US keyboard set to UK input - but on your laptop it is actually the \ key!). This should provide a backslash!

altGR+#( \ )key

If you do not have Alt GR in your keyboard, simply press and hold left ALT then type 92.