[header] How to shop at gum in moscow [title] Prepare a few forms of payment like a credit card or debit card. [step] If you want to use cash, be sure to convert your home currency into the russian ruble. [substeps] Call your bank to tell them you will be traveling to moscow to avoid your credit card or debit card being declined. 
As a matter of procedure, banks flag any purchases that are made far away from home in case of theft. Usually, calls have to be made to reactivate the card before making further purchases.