A monitor is 21 inches by 12 inches.  There are 100 dots per inch.  How many total pixels are there?
The display is 21*100=<<21*100=2100>>2100 pixels across
The display is 12*100=<<12*100=1200>>1200 pixels tall
That means there is a total of 2100*1200=<<2100*1200=2520000>>2,520,000 pixels
#### 2,520,000