2.1.967 Part 1 Section, IMPOWER

a.   The standard does not mention error case of argument complex-number equal to zero and argument n is not a positive number.

Office returns #NUM! if complex-number is zero, and the exponent n is not a positive number.

b.   The standard specifies that y is the exponent to which complex-number is to be raised as well as a coefficient of the argument complex-number.

Office treats n as the exponent to which argument complex-number is to be raised.

c.   The standard does not fully specify how the angle θ is calculated.

Office calculates angle θ as ATAN2(x,y).