To estimate heart rate from a 30-second ECG, you multiply the count of QRS complexes by:

To estimate heart rate from a 30-second ECG, you multiply the count of QRS complexes by:

• A. Divide by 60
• B. Multiply by 2
• C. Divide by 2
• D. Multiply by 1

Answer: (B)

Estimating heart rate from a 30-second ECG relies on converting a half-minute count into beats per minute. Count how many QRS complexes appear in 30 seconds, then multiply that number by 2 to scale up to a full minute. This works because a minute is twice as long as 30 seconds, so doubling the count gives the heart rate in bpm. For example, 15 QRS complexes in 30 seconds would estimate 30 bpm. If the rhythm is irregular, you might take multiple 30-second counts or use a longer strip for averaging. Dividing by 60 would give a per-second rate, not bpm; dividing by 2 would halve the count; multiplying by 1 changes nothing.

Estimating heart rate from a 30-second ECG relies on converting a half-minute count into beats per minute. Count how many QRS complexes appear in 30 seconds, then multiply that number by 2 to scale up to a full minute. This works because a minute is twice as long as 30 seconds, so doubling the count gives the heart rate in bpm. For example, 15 QRS complexes in 30 seconds would estimate 30 bpm. If the rhythm is irregular, you might take multiple 30-second counts or use a longer strip for averaging. Dividing by 60 would give a per-second rate, not bpm; dividing by 2 would halve the count; multiplying by 1 changes nothing.