PHPExcel keep leading 0s in number

In EXCEL columns from PHPExcel, I want to display number 2 as 0002.
After setting the cell value, 
For cell F1:

$objPHPExcel->getActiveSheet()->getStyle('F1')

->getNumberFormat()->setFormatCode('0000');

For cell F1 to F1000:

$objPHPExcel->getActiveSheet()->getStyle('F1:F1000')

->getNumberFormat()->setFormatCode('0000');

To get all columns align left

 
$objPHPExcel->getActiveSheet()->getDefaultStyle()

->getAlignment()

->setHorizontal(PHPExcel_Style_Alignment::HORIZONTAL_LEFT);

For cell F1 to F1000 align left:

$objPHPExcel->getActiveSheet()->getStyle('F1:F1000')

 ->getAlignment()

 ->setHorizontal(PHPExcel_Style_Alignment::HORIZONTAL_LEFT);