The following steps will show you how use Math Calculation tool in a combination with Integrator feature.
Go to General Configuration tab in the iConstruct menu and click Integrator Configuration button.
Under Item/Group Data Mapping details define Model Tab and Model Tab Property. Go to the Options tab and choose Perform Calculation from the drop-down list.
Choose the desired Calculation (Total Volume in our example) and click OK.
Go to Integrator Configuration ➤ Define Model Tab ➤ Select Model Tab Property ➤ Click on the Options tab ➤ Choose Perform Calculation ➤ Select the Calculation ➤ Click OK