```ruby
class AddNumberToProofAttempt < ActiveRecord::Migration
  def change
    add_column :proof_attempts, :number, :integer, null: false
  end
end
```

Define default proof status number.
user
```ruby
class AddNumberToProofAttempt < ActiveRecord::Migration
  def change
    add_column :proof_attempts, :number, :integer, null: false, default: 0
  end
end
```
assistant