Answer:
64,000,000
Explanation:
To find out how many combinations there are, you first must do an equation of multiplying these numbers.
20×20×20×20×20×20
Reason being: There are six different number combinations that all are between 1 and 20, so you must multiply all of these numbers.
If you multiply them all together, you would get 64,000,000 different combinations.
Hope it helped!