In this tutorial Dave demonstrates the seldom used and often little understood mathematical integration function available on your modern digital oscilloscope.
And demonstrates a practical example use for it in accurately measuring the total power consumption of a microcontroller that sleeps and then wakes up and does some processing before shutting down again. By getting the total area under the current curve.
For more detail: EEVblog #662- How & Why to use Integration on an Oscilloscope