Using digits of 1999 in that order and operations +, -, x, /, and brackets can you make any of the numbers from 1 to 20?

Question

How many different numbers can you make if you use the digits 1, 2, 3, 4 once each, in any order, and a times sign. For instance 31x24, or 2x413.

Answer 1

19 - 9 - 9 = 1
(1×9 + 9)/ 9 = 2
1 + (9+9)/9 = 3
-1 + 9 - (9/9) = 7
-1 + 9 - 9 + 9 = 8
1 + 9 - (9/9) = 9
(1 + 9)/(9/9) = 10
(1/9) × (99) = 11
1 + (99/9) = 12
19 - (9/9) = 18
19 - 9 + 9 = 19
19 + (9/9) = 20