ROUNDDOWN Rounds a number down, toward zero.
Syntax
ROUNDDOWN(number, num_digits)
Parameters
Number – A real number that you want rounded down.
Num_digits – The number of digits to which you want to round. Negative rounds to the left of the decimal point; zero to the nearest integer.
Return Value
A decimal number.
Reference Data
https://docs.microsoft.com/en-us/dax/dax-function-reference