public class Formatter { String roublesFormat; double paid; public String formatPaid(double paid) { this.paid = Math.floor(paid) % 10; if (this.paid == 1.0) { this.roublesFormat = "рублю"; } else if (this.paid > 1.0 && this.paid <= 4.0) { this.roublesFormat = "рубля"; } else { this.roublesFormat = "рублей"; } return String.format("%.2f " + this.roublesFormat, paid); } }