Hi student! 

Great question! 

I can't speak for the math section but only for the Writing and Reading sections.

My simple answer is No. Don't use the old SAT tests to prepare for the Digital SAT. 

There are too many changes that studying from old SAT exams is going to be very inefficient and doesn't make sense to me. 

The long answer is...

The Digital SAT tests you on FEWER grammar concepts and question types compared to the Paper SAT. 

The Digital SAT doesn't test you on "Placement" "Yes/No" "Logical comparisons" and "reading comprehension-style questions." 

So, although it is okay to use the paper SAT tests to study the Writing section, 

just know that some of the questions you answer from the SAT Writing section will not appear on the Digital SAT, 

but overall, if you need extra study materials to practice, using old SAT Writing tests isn't a bad option. 

The Reading section for the Digital SAT is VERY different from the Paper SAT. 

Doing Reading from the paper SAT, in my opinion, is simply a waste of time. 

The best option is to find Digital SAT materials to study from. =)

I hope this helps! 

Best of luck and Keep moving forward!

You Got This!