?FromDigits

ds = IntegerDigits[123]

Not[
      Or[ds[[1]] == 
          ds[[2]], 
        ds[[1]] == 
          ds[[3]], 
        ds[[3]] == 
          ds[[2]]]]

Length[
      Select[Table[k, {k, 100, 999}], 
        And[EvenQ[#], 
Not[
              Or[IntegerDigits[#][[1]] == IntegerDigits[#][[2]], IntegerDigits[#][[1]] == IntegerDigits[#][[3]], IntegerDigits[#][[3]] == IntegerDigits[#][[2]]]]] &]]

Select[Table[k, {k, 100, 999}], 
      And[EvenQ[#], 
Not[
            Or[IntegerDigits[#][[1]] == IntegerDigits[#][[2]], IntegerDigits[#][[1]] == IntegerDigits[#][[3]], IntegerDigits[#][[3]] == IntegerDigits[#][[2]]]]] &]

64*4 + 72

10 9 8 7 6 5 - 9 8 7 6 5 4

bin = 6*9 8 7 6 5

big = bin

nbng = 8 7 6 5 4 3

allp = 10 9 8 7 6 5

borgorbg = allp - nbng

big + bin - (allp - nbng)

6*5*8 7 6 5