Amazing! OK, let's summarize what we've learned today. We know the following principles:

• Computations in floating point numbers are not always exact. Use decimal numbers for all money columns and when precision matters.
• Dividing two integers is an integer division. Use CAST(column AS type) to avoid errors.
• Avoid division by zero. For now ...

We've also learned some useful functions:

• mod(x,y) or x%y – returns the remainder of division of x by y.
• round(x) or round(x,p) – rounds the number to an integer or to a specified precision (p).
• ceil(x) – rounds up to the nearest integer value.
• floor(x) – rounds down to the nearest integer value.
• trunc(x) or trunc(x,p) – always round towards zero to an interger value or to a specified precision (p).
• abs(x) – returns the absolute value of x.
• sqrt(x) – returns the square root of x.

The queries we've written so far were fairly simple. Let's test your knowledge with more advanced examples.