The fact that A and D are lined up on the left side of the cell would indicate that they're there as text, not as numbers. What you'll need to do is create a couple of temporary "helper columns" so as to convert the text into values. The formula =VALUE(A2) copied down in the column to the bottom of all these rows will turn 43619 into whatever value it is; then you'll be able to format that value as a date. Once that's done, assuming you want it in column A, you can select the entire column from that temporary helper column and do a Copy.....Paste Special .... Values and Number Format from the helper column into column A. Just make sure you use Copy and Paste Special ... Then the same with column D.