I need to create field for custom object and the field type requirement is Number with floating-point decimal. How to do that? Should I select data type Number with 2 decimal ?   
Field Type: Number with floating-point decimal  

I created a detail object connected with Account as Master-Object that contains mainly 2 fields: Date (YYYY) and Currency Value.

I would like to display on the Account the Currency Value of the youngest entry in the associated theme list i.e. the value of 2010 in 2021.

Do you hav recommendation what type of field to use and if it is a formula field, which formala? 

Thank you very much