sorry my quesiton is not clear . after reading the post about how to prepare for SBB exam. i am motivated to read from now and prepare for the SBB some day in the future hopfully :tongue: SBB defintely my ultimate goal . i want to learn all about blood bank with all of your help here. you are the best truly . i read the section with some math in exam review i have no idea, i forgot all about math and how to calculate propaliblity ..molarity . please advise me any nice book to refrensh my math other. Thanks Malcom for your respond