156280

1. 1,2,3 or 3,2,1

2.impossible:some 4 digit numbers are divisible by 4, but not divisible by 3
example:4321/4=1078
4321/3=1440r1

3. impossible:because it must be a 5 at the unit place,but the 4 times table does not have
any numbers end in 5
example:4x1=4
4x2=8
4x3=12
4x4=16