You can check the total number of pages fed through the printer. The information is printed together with the nozzle check pattern.
Load A4-size plain paper in the printer.
Press the 
button to turn off the printer.
Turn the printer on while holding the 
button down, and then release the buttons when the power light flashes.
You can also check the total number of pages fed from the printer driver. See the related information link below for details.