Determine the monthly payment with micro:bit code

The Problem:
You want to buy a PS5 for $600 and plan to finance it monthly for 1 year. The annual interest rate is 21%, compounded monthly. How much should your monthly payment be?

You will write a program that:
-Takes an estimated monthly payment and determines the balance after 12 months of payments & compounding interest
-Adjusts the estimate (moving down by $0.01) until finding a payment that leaves the balance sufficiently close to $0 after 12 payments.