For a month number in column A, I want the LAST day of that particular month in column B. Right now, I'm working with year 2014, so:

```
A1 number is 1 so B1 date is 01/31/14
A2 number is 2 so B2 date is 02/28/14
A3 number is 11 so B3 date is 11/30/14
A4 number is 10 so B4 date is 10/31/14
```

etc. for all twelve months of the year 2014. I will eventually need the same for year 2015, 2016 etc.