Answer:
Step-by-step explanation:
This is what I am thinking. Â - ,- ,- , - Â I number goes in each space. Â There are 10 numbers to choose from and I cannot use a digit more than once. Â I only have 1 choice for last slot and that is the number 7. Â I have 9 numbers left . Â I could put any one of the 9 numbers in the first spot, then there are only 8 numbers to choose from, so I will put 8 in the second spot. Â I now have only 7 numbers that are left for the third spot.
If I multiple this together 9x8x7x1 = 504