Go to a specific relative number line in Neovim

I am trying to use relative line numbers with NeoVim to jump through my file so I am expecting to digit to jump 20 lines before:

:20k 

and to jump 20 lines after:

:20j

I tried but nothing happens.

So I tried to add this configuration to my init.v file:

nnoremap <expr> j v:count ? 'j' : 'gj'
nnoremap <expr> k v:count ? 'k' : 'gk'

But when I insert something like: :20j it gives me this error:

E471: Argument required

How can I achieve my goal?

>Solution :

You can achieve your goal by learning properly how to use your tools. I don’t know if Neovim still has it but Vim comes with $ vimtutor for the basics and you can still probably follow :help user-manual.

Case in point, it is 20j, not :20j.