How do you get the answer to 36x45?
The answer is 1620.
To get that, you would first multiply 36 and 5. That gives 180.
Then multiply 36 times 4 (actually, multiply by 40, but we'll get
there). That gives you 144. But you really wanted to multiply by
40, so tack on a zero and get 1440. Then add the 1440 to the 180.
Then you get 1620.