I'm sure this is somewhat simple, but I just can't figure it out. I have two
columns - A lists a unique number, and B lists all the times this number was
used (other details were cut). So I think it makes A to B one to many.

I need a formula that will confirm or show evidence that all records in A
were used in B, and if any were missed point this out. I have been trying
vlookup with no luck. Example layout below - I would like column C to say if
each number in A was used in B. Thanks in advance.

A B
1 1
2 1
3 1
4 2
5 2
3
4
5