What is the correct procedure for calculating a regular heart rate interrupted by premature beats?

What is the correct procedure for calculating a regular heart rate interrupted by premature beats?

▸ Calculate the range slowest to fastest using the memory method and the mean rate using the six-second strip method.

▸ Calculate the range fastest to slowest using the little block method and the mean rate using the six-second strip method.

▸ Ignore the premature beats and calculate the heart rate using the little block or memory method.

▸ Ignore the premature beats and calculate the heart rate using the six-second strip or memory methods.