A vast majority of Vatican City stamps are issued in sheets of denominations of 10 (40, 50 or 100 stamps) depending on the printing process. The stamps were issued in rows of 8 or 10 with 5 stamps in a column, or in 10 by 10  sheets.  

In a few occasions stamps were issued in sheets of 64 (8 x 8) or 56 (7 x 8).  In order to keep the math simple, an upper corner block of 4 or 6 of each set contained the marginal inscription usually seen in the margins around the sheet.  This is usually "Il Foglio di sessanta Francobololli ..." which is "A sheet of 60 stamps...".  The stamps surrounding the inspiration block is known as an ornamental block