user: Question: How many companies have POSTERMOBILE LIMITED as a parent company?
Columns: ['COMPANY NAME', 'Holding Companies', 'Subsidiaries', 'Description of activities', 'Parent (holding) company']
Types: ['text', 'real', 'real', 'text', 'text']
Sample row: ['APOLLO DOMINION INVESTMENTS LIMITED', 5.0, 0.0, 'Investment holding company.', 'BESCOT ENTERPRISES LIMITED']
SQL:

assistant: SELECT COUNT("COMPANY NAME") FROM "Table" WHERE "Parent (holding) company" = 'POSTERMOBILE LIMITED';