I am a Sec 2 student from Singapore, and I'm pretty new here. I'm not sure whether this is the correct place to put this type of things or not, but anyway, just give it a try. I have just developed an app called PSLE Aggregate Calculator available only on Google Play Store(Can't develop for iPhone because I'm not really familiar with the language and putting iPhone apps on AppStore needs US$99 a year).
The App can estimate the aggregate score for PSLE from SA and prelim results, with accuracy depending on the information input(average score and standard deviation).
It's free , just search zbz_lvlv, which is my developer username on Google Play store. You will find it there. Should you have any questions, you can ask me here.
for your support !