Abstract: A cardiotachometer for indicating heart rate of a user in beats per minute. The cardiotachometer comprises a sensor, placed on the body of the user, for producing an electrical signal indicative of the heart rate of the user. Circuitry is provided for converting the electrical signal into first and second digital signals. 60/t computation circuitry responds to the first and second digital signals and produces a third digital signal having a varying frequency representative of the number of heart beats per minute. An up-counter converts the third digital signal into a plurality of binary number signals, each bit of which is stored in a series of shift registers. A compare using a plurality of exclusive OR gates, compares each of the stored binary number signals with the most recent binary number signal, from the up-counter, to determine if a plurality of compared signals are within a predetermined percentage of each other.