Does anyone know if I apply to the computer science section, do I need to complete the math problem set, in addition to the computer science problem set?
In general. CS ‘requires’ only general problems. But that should not stop you from trying advanced ones. You never know which ones you will actually get right, so no harm trying.
Also, in the past years, some students have achieved up to 95% , 98% in problem sets and still were rejected so take your time and solve as much as you can. Some are designed to be solved by only a few in whole country so let that not be factor in your efforts.
FYI,
Admission decisions are out for PRIMES USA and PRIMES local math. CS not out yet.