9,876 since these are the largest single digit numbers that can be done without repeat.
9,876,543,210 9876543210
9875.
9999 - 102 = 9897
9999-1023 = 8976
997 is the largest 3-digit prime number.
Assuming you can use each digit only once, the logical answer has to be 9,876,543,210 (since you would want to use the largest numbers in the highest value places).
93,876
93876
679 is the product of the largest single-digit prime number and the largest two-digit prime number.
If leading zeros are not allowed to make the numbers, then largest = 9876, and smallest = 1023. To get the difference, just subtract: 9876 - 1023 = 8853
Largest 4 digit number with repetition is 9999 Largest 3 digit number without repetition is 987 Difference is 9999 - 987 = 9012.