16. Fill in each square in $\square \square+\square \square=\square \square \square$ with a digit from $0, 1, 2, \cdots \cdots, 9$ (digits in the squares can be the same, and the leading digit of any number cannot be 0), so that the equation holds. 

There are
【Analysis】If the first number is 10, the second number can be from 90 to 99, which gives 10 ways to fill it.
If the first number is 11, the second number can be from 89 to 99, which gives 11 ways to fill it ......
If the first number is 89, the second number can be from 11 to 99, which gives 89 ways to fill it.
If the first number is from 90 to 99, the second number can be from 10 to 99, which gives 90 ways to fill it, totaling $10+11+12+\cdots+89+90 \times 10=4860$ ways to fill it.