Final answer:
Most ECGs use 12 lead electrodes, with six electrodes placed on the chest and four on the limbs.
Step-by-step explanation:
An electrocardiogram (ECG) typically uses 12 lead electrodes. Six electrodes are placed on the chest, and four electrodes are placed on the limbs. By careful placement of these surface electrodes on the body, it is possible to record the complex electrical signal of the heart, which is represented as the ECG.