and for the tram
we bought a 72 hours ticket last time and it costs 15 euro
you are allowed to take every gbv-tram or bus 72 hours from the point you stamp it
imo much better than the strippenkaart because you can just drive around the city and stop where you want.
or if you just want to go to the dam from the central station after a visit in a great shop, you can drive.
so if you want to stay for more than a single day it is worth to buy one of these tickets
24 hours about 7 euro
48 about 13 euro
72 definitely 15 euro...
cannot remember the shorter ones exactly
and you can buy them in every tourist office