Factor of 6=2,3
If 123X43Y is divisible by 2 then its unit digit should be 0,2,4,6,8 and the number for being divisible of 3, the sum of its digits (13+X+Y) should be divisible by 3
Hence,
X+Y=2
So,
When X=0,Y=2
Therefore the number is 1230432.
Or
When X=2,Y=0
Therefore the number is 1232430.
As per the given condition of the smallest number, the correct answer is 1230432.
Hence, this is the answer.