Manually create the compound interest formula without functions using the following format: =((fv/pv)^(1/n))-1. Here, n is the number of years between the future value (fv) and present value (pv). Replace the variables with actual values or references to cells that contain actual values, such as =((C2/C1)^(1/B3))-1 or =(($180,000/$100,000)^(1/5))-1..