Crossword Clue:

the act of adding

Answer	Crossword Clue
ABACUS	Ancestor of the adding machine
ZERO	Main character of Elmer Rice's "The Adding Machine"
THEME	Adding certain letters to phrases to mark the 30th anniversary of the seminal "Elk Cloner" computer virus, e.g.

ZERO	"The Adding Machine" protagonist
RICE	"The Adding Machine" playwright
HIRING	Adding to the payroll
TASTY	Worth adding to the menu
PASTINGIN	Adding to the scrapbook, e.g.
TIPPING	Adding 15 for the waiter, say%
SCALE	Device for adding up the pounds
POSSES	Noun that becomes a verb by adding an "s" at the end

ANY	Quantity that makes another quantity by adding an "m" at the front
IRA	The annual due date for adding money to one is April 15th: Abbr.