If P(A) denotes the probability of getting an event A. Then P(not getting A) is :

1. 1 - P(A)

2. P(A) - 1

3. P(A)

4. 1 + P(A)

The probability of not getting an event is the complement of the probability of getting the event, which is,

P(not getting A) = 1 - P(A)

Hence, option 1 is the correct option.