row

 floatingActionButton: Row(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          FloatingActionButton(
            onPressed: () => _counterBloc.onIncrement(),
            tooltip: 'Increment',
            child: Icon(Icons.add),
          ),
          SizedBox(width: 10),
          FloatingActionButton(
            onPressed: () => _counterBloc.onDecrement(),
            tooltip: 'Decrement',
            child: Icon(Icons.remove),
          ),
          SizedBox(width: 10),
          FloatingActionButton(
            onPressed: () => _counterBloc.onMultiply(),
            tooltip: 'Multiply',
            child: Text('X'),
          ),
          SizedBox(width: 10),
          FloatingActionButton(
            onPressed: () => _counterBloc.onDivide(),
            tooltip: 'Divide',
            child: Text('/'),
          ),
        ],
      ),