To buy MTR ticket for six person to visit Hong Kong in 5 days. Stay at Tsim Sha Tsui.

You can buy Group Tickets for the ride on Airport Express Train. Since you have six persons, you may buy one Group of Two ticket, and one Group of Four Ticket. The Group of Two ticket costs HKD 170 between HKIA and Tsing Yi; HKD 250 between HKIA and Kowloon; HKD 280 between HKIA and HK Station. The Group of Four ticket costs HKD 100 between HKIA and Tsing Yi; HKD 150 between HKIA and Kowloon; HKD 170 between HKIA and HK Station.

To visit these attractions, you are advised to buy Standard Octopus Cards, with which you can ride on Airport Express, metro, buses, taxis, trams, ferries, etc. Each adult needs to pay HKD 50 as the refundable deposit, and HKD 100 as the stored value. Each child aged 3 to 11 needs to pay HKD 50 as the refundable deposit, and HKD 20 as the stored value. One card can be used by one person only. So you need to buy six card totally. :)