Per the Help file:

Number: 2 additional settings are visible for numbers:

• Check Auto to get an auto-increment number. If you manually change the field value and that value already exists, the change is cancelled and a warning is shown as a pop-up notification
• Format: Enter a specific format or select one of the built-in ones. e.g. 0 to format a number without decimals, 0.00 for 2 digits after the decimal point. See Hints section below

  I am not able to find a Format option for numbers. I can only select blank, standard and currency.
  Trial and error, shows that:
  A. Blank doesn't force any decimals
  B. Standard always shows numbers with 2 decimals
  C. Currency always shows numbers with 2 decimals and $
    
  How do I format Currency w/o decimals "0"?