How do I display unique numbers in single cell?

I have a 5 digit number. For eg 23450 in one cell. I want to diplay missing number from this number. my other cell should display 16789 which are missing from 0 to 9 series. Below is example

Column A        Column B (should display missing number)
23456          17890
34877          125690
22344          1567890
27788          1345690

Can anybody help on this..