Cat food inflation increases 2% each month

I buy one bag of cat food at the end of each month and now costs $50 for a bag

I want to open an account where I invest in it at the beginning of each month, let it earn interest, and then buy the cat food.

01 what nominal interest rate do I need to pay $50 now and pay for cat food in 1 month? 02 if I nd an account that makes 0.4% per month what should I invest now at the beginning of the month to buy cat food at the end of the month? 03 what do I need to invest in 10 months