This Extra Field Type is available in Profile Builder 2.0, Hobbyist or Pro.
You can use this extra field type to allow users to add a number.
You can specify the field title, meta-name to be stored in the database, description, default value, minimum number value, maximum number value and number step value.
Also, you can set whether this field should be required or not.
This is how it looks like in the front-end.