The FLOOR() function round the specified number down, and return the largest number that is less than or equal to the specified number.

FLOOR function examples

SELECT FLOOR(1.2) FROM DUAL; 		-- output : 1
SELECT FLOOR(1.5) FROM DUAL; 		-- output : 1
SELECT FLOOR(1.7) FROM DUAL; 		-- output : 1
SELECT FLOOR(1.99) FROM DUAL;		-- output : 1
SELECT FLOOR(-1.2) FROM DUAL; 		-- output : -2
SELECT FLOOR(-1.5) FROM DUAL; 		-- output : -2
SELECT FLOOR(-1.7) FROM DUAL; 		-- output : -2
SELECT FLOOR(-1.99) FROM DUAL; 		-- output : -2
SELECT FLOOR(20.9) FROM DUAL; 		-- output : 20
SELECT FLOOR(-5.1) FROM DUAL; 		-- output : -6
SELECT FLOOR(-100.01) FROM DUAL;	-- output : -101
SELECT FLOOR(1000.99) FROM DUAL;	-- output : 1000

References

1. FLOOR Function :- Oracle official docs