How many SAT do we need to take?

Test Preparation
1

What is the difference between ACT and SAT?

2

@south12345 For test-optional schools, zero. For schools that require the SAT or ACT, you only need to take either once (though you could take either multiple times if you wish). Note that some schools recommend or require SAT subject tests, and/or require SAT/ACT with the essay.

I suggest googling this one.