code: int getPrefixedDigitArea() {
  
          if (this.multi == null) {
              return 0;
          }
  
          int digits = 0;
  
          for (int i = 0, n = this.multi.length(); i < n && Character.isDigit(this.multi.charAt(i)); i++) {
              digits++;
          }
  
          return digits;
  
      }
docs: count of leading digits