Floor
                Floor() rounds x down to the nearest multiple of step [+ offset]. The default value of offset is 0.
Compare with the ceil function, which rounds input numbers up.
Syntax:
Floor(x[, step[, offset]])
Return data type: numeric
Examples and results:
- Floor( 2,4 ): returns 0
 - Floor( 4,2 ): returns 4
 - Floor( 3.88 , 0.1 ): returns 3.8
 - Floor( 3.88 , 5 ): returns 0
 - Floor( 1.1 , 1 ): returns 1
 - Floor( 1.1 , 1 , 0.5 ): returns 0.5