Multitesters have many uses, and one of the handiest is testing common household batteries. A weak or dead smoke alarm battery in a fire, or a dim flashlight bulb during a blackout, can be downright dangerous. Pull out that multitester and check those vital batteries so they're ready when you need them.
Insert the black probe into the (-) terminal, and the red probe into the (+) terminal. Rotate the voltage selector switch until it points to the voltage you're testing, and then test batteries as shown in Photos 1 and 2.