automatic numbering of members and built a calculator

Hi there my name is Jacky Chery: I will be using [login to view URL] to build my social platform. However, I need some capabilities. 1st: I need the website to automatically assign a numerical number to each member that creates a profile in the order of which they sign up. for example the first person who sign up will have #1 next to their name or somewhere on their profile. the next person will be number two and so forth. 2nd: I need a custom made calculator to be added as a page. the calculator will help members find their sponsor's number. For instance, every member will be assign 3 people. if I am number # 1 : ( I will be assign #2 # 3 #4) so if the number 2 person puts his number in the calculator, it will show that # 1 is his sponsor. if number 3 puts his number, it shows that # 1 is his sponsor. if number the person who is # 4 types his number, it will show that # 1 is his sponsor. However, if the person who is # 5, # 6 # 7 there number in the calculator the result should show that # 2 is their sponsor. if number 300 type his number, the calculator should tell the person what number is his sponsor. So I only need those two features added to the platform. Please advise. Thank you!