Create an Excel file ( or a picture) with 6 separate spreadsheets that make it SUPER EASY (fill in the box type thing**) for someone (like your grandma) to determine the following:
Monthly mortgage payment for N years
How much do I need to save now for when my kid (assuming at 18 years old) goes to college, and include a way to determine the amount of years left to save (i.e. 18 minus kids age
Compare a car loan vs a lease
How much do I have to save for retirement: Include a box for: goal amount, age, retirement age, frequency of deposit (which affects your interest rate), interest rate. Assume the amount of deposit does not change the entire time
If I buy an asset that is worth X now, how much will it be worth at time Y, given Z interest rate and a given period of analysis with a certain compounding frequency
Someone wants to sell me an investment worth X in Y time, determine the value of the investment given all the parameters, including the initial cost of the investment. Do I invest
As in, put your interest rate here, put your time (in years here), put the value of the asset here, how long will the lease be (in years/months,etc)?, how long will the loan be?, how frequently in one year does it compound, etc etc.