Tickets, cards and what pays off
Three fares interest a visitor: the single, the rechargeable multi-ride card and the unlimited day pass. The arithmetic depends on how many rides you take per day.
Single vs. multi-ride
The ten-ride card is considerably cheaper per journey and sells at any station machine. At three rides a day you're already halfway to amortizing it; at four, clearly.
Tourist day passes
Multi-day unlimited passes include the airport and the whole network: they only pay with genuinely intensive use. Count your planned rides per day before deciding — the ten-ride card almost always wins.
Where to buy without markups
Station machines and the official apps sell everything without surcharge; tickets resold at the airport door with tourist branding, not always. Card payment works at any machine.