To completely eliminate the need to worry about what 0 x 1is, and risk confusing 0 or Undefined, you should follow PE(MD)AS. (The M and D can be either MULTIPLY or DIVIDE can be switched, depending what comes first in the order of the equation.)
Thus,
242 - 242 (1) = two-hundred forty-two minus two-hundred forty-two times one
242 - 242 = two hundred forty-two minus two-hundred forty-two.
0= zero
:)