Sellers can list tickets in any combination on StubHub. If they sell the tickets in multiples of 2 or 4, you can't buy 1 or 3 of the tickets.

Finding a specific number of tickets on a computer

1. Go the event
2. Under 'Number of tickets' choose the ticket quantity you want

1. Go the the event. 
2. At the 'How many tickets?' pop-up, choose the ticket quantity you want
3. Tap 'View tickets'

To change the number of tickets

1. Tap 'Filter'
   
2. Under 'Number of tickets' update the ticket quantity
   
3. Tap 'Apply'