I found a very good application named "power calculator" (scientific calculator which can solve many complex math problems) and installed it.
Before installing "power calculator", I followed exactly the instructions of the web site (install qt pack for s60v5 on my nokia 5230, then install power calculator). However, when i opened the application, the letters and numbers appeared to be unreadable. Here is its pictures (on the left is the sample and on the right is the real situation on my phone):
I also followed the steps of intalling qt pack (install qt v4.7.3 and then qtmobility), but the result wasn't as good as one demonstrated in the video.
Please instruct me how to overcome this problem. Many thanks!
P/S: If anyone have the full version of touchmaths v.3, please show me where to download it. The applications on the internet are all trials (some functions such as equation, calculations, equations system, etc. are very limited).