To get the mass of an object using a triple-beam balance, sum up the notch readings of the rear beam weight, middle beam weight and front beam weight. Each notch on the middle beam, rear beam and front beam represents 100-gram, 10-gram and 1-gram weight increments, respectively.
For example, if the middle beam weight reads 300 grams, the rear beam weight reads 70 grams and the front beam weight reads 3.25 grams, then the total weight of the object is 373.25 grams. In a triple-beam balance, no additional weight is necessary. The user simply slides the weight along each beam onto the appropriate notch until the object on the pan and the weights are in equilibrium.
The object to be weighed can be placed directly on the pan. But before doing so, set the balance reading to 0.00 grams by adjusting the little knob under the pan. This ensures that the object is weighed accurately. If a container is used to hold the object to be weighed, the empty container must be weighed first. Then the object with the container is weighed next. To get the weight of the object, subtract the weight of the empty container from the weight of the object with the container.