National University of Singapore

Your class 12th score is low, as they generally require at least 60 percent in the boards and you have a lot less so not sure about passing the criteria.

If you get good score in SAT with good score in subject test and good extracurricular activity, you may surely get a call from the University of your Choice.

You need to have at least 65 percent in your boards. If you do not have that, then you are not eligible for most colleges. Try for lateral entry if possible.

Hello, you need to appear for english language proficiency test of IELTS or TOEFL and GRE or GMAT
you need to have a very good academic score
http://www.nus.edu.sg/admissions/graduate-studies/graduate-admissions.html.

Hello,
Requirements for NTU is at least 90% in all subjects including English but excluding the other languages in the Standard 12 Board exam. Requirements for NUS is candidates should have a minimum GRE score of 320 (verbal & quantitative) and 3.5 (analytical), or a GMAT score of 650 and above. The minimum TOEFL scores for Internet Based Test (IBT) is 90; or IELTS score of 6.0.