How should I use numeric prefixes in config.toml

[geometryolife]

In Vim. I use the configuration below to move up/down quickly:

noremap K 5k
noremap J 5j

But I don't know how to set up in Helix configuration.

[the-mikedavis]

This will be possible with macro keybinding #1383:

[keys.normal]
K = "@5k"
J = "@5j"

Until then it is also possible to accomplish this by repeating the commands in config:

[keys.normal]
K = ["move_line_up", "move_line_up", "move_line_up", "move_line_up", "move_line_up"]
J = ["move_line_down", "move_line_down", "move_line_down", "move_line_down", "move_line_down"]