By counting the number of QRS complex we can determine the

By counting the number of QRS complexes that occur in a given time period, one can determine the heart beat rate of an individual. Generally we count the number of R waves on the ECG in six seconds duration and multiply by 10 to get the heart rate. For example, if you find 7 R waves in six seconds, the heart rate can be calculated as 7x10=70 bpm.