How To Figure Out Compound Monthly Interest on Credit Card Debt in LO Calc?

I have credit card that I make different monthly payments on. I would like to figure out the interest on each payment based on the principal and the monthly compunded interest rate. I will upload what I have in a Calc Spread for analysis.

Thank you for any assistance!

Credit Debt.ods (18.0 KB)

I may have figured it in spite of myself. I thought I would need a financial function. My goal was to apply monthly payment, adjusting for the interest, to the principal until the card is paid off. I may have accomplished this. Now I just don’t know if its accurate.

Credit Debt.ods (21.6 KB)