Numeric but can be blank

I have a form that includes the following

Forms\Components\TextInput::make('company_number')
    ->label('Company Number')
    ->numeric()
    ->nullable(),

Forms\Components\TextInput::make('company_number')
    ->label('Company Number')
    ->numeric()
    ->nullable(),

Forms\Components\TextInput::make('company_number')
    ->label('Company Number')
    ->numeric()
    ->nullable(),

Forms\Components\TextInput::make('company_number')
    ->label('Company Number')
    ->numeric()
    ->nullable(),

However, when I try to submit the form, if this field is left blank, I get the following validation error

The company Number field must be a number.

Is there a way to require the field to be numeric or blank?

Also as a slight aside, how do I capitalise the 'c' in the validation error?