The thing is, the use of a graphical calculator is now mandatory in high school level maths since about 12 years or so. So anyone who's taken maths from 15-16 on in a Dutch school in recent years (which is everyone at the higher levels, since some math, including basic statistics, is mandatory for everyone) has a TI-83 or similar (or newer models, but they seem quite similar to me). They're actually nice things to have on hand for quick calculations.
One problem is of course that some students have a pretty good grasp of how the thing works, but no idea what they're doing.
1.65 is 0.4505 as you state. That means everything from the left of that line to the 50th percentile is 45.05% of the populations. In addition to that you have another 50% of the people below the 50th percentile. That's a total of 95.05% below this z score.
Your question was what is the probability of getting a score above this? So...
100-95.05=4.95% (.0495) which is what DancerTiffy gave you. It's good to remember how to do this because I now use a computer program to do all of these calculations for me.