3 * (2 - 1)
9
012258
6 for 3-digits, 6 for 2-digits, 3 for 1-digits, and 15 for all of the combinations
111, 121, 222, 212
3*3*2*1 = 18 of them.
123,456 would be the smallest number using all 6 digits. You arrange the numbers from lowest to highest.
6
write the largest number you can make using each of the digits 7,1,0,2, and 9 just once
Six, if you don't repeat any digits.
0478
111, 121, 222, 212
The highest number you can make out of the digits 2 4 0 and 1 is 4210.