Knowing your blood type is very useful and sometimes vital in an emergency. For this there are not 36 solutions, you have to take a blood test. All you need to do is ask your doctor to add blood group testing when you have a blood test. Note that you will need to perform two analyzes to confirm your group.
Note that it is interesting to know your group in order to donate blood more often. O- donors are universal donors, hence the importance of donating blood if you have this blood type. People in group AB- are universal recipients, being in this group you have the chance to receive blood from any group.