Learn Microsoft Excel - How To Use FLOOR() Formula

Syntax
FLOOR(number,significance)
The FLOOR function syntax has the following arguments:
Number : Required. The value you want to round.
Significance : Required. The multiple to which you want to round.

Note:
If either argument is nonnumeric, FLOOR returns the #VALUE! error value. 
If number is positive and significance is negative, FLOOR returns the #NUM! error value. 
If the sign of number is positive, a value is rounded down and adjusted toward zero. If the sign of number is negative, a value is rounded down and adjusted away from zero. If number is an exact multiple of significance, no rounding occurs.