Hint: It has nothing to do with construction or buildings. Instead, it is rounding numbers with a twist. FullCityConsulting explores floor and ceiling functions in their weekly post:
A few weeks ago we looked at the Min and Max functions. That got me wondering if there are any other FileMaker functions that travel in pairs. I found a few, but the most apt to follow Min and Max have to be Floor and Ceiling. Where Min and Max examine a range of values to determine the lowest or highest values, Floor and Ceiling each take a single number and return the closest lower or higher integer.
Essentially Floor and Ceiling are specialized types of rounding. The rounding we all learned in elementary school tells us to choose the closest whole number when starting with a decimal value. For example 5.2 rounds down to 5 and 7.6 rounds up to 8. With Floor, any decimal value at all will result in rounding down. Ceiling rounds everything up.
Read the whole thing to see the difference between these functions and the Int function.