Don't miss that in Excel when you want to reference a date in another column (that is formatted as a date, not as text) in a formula in another cell and display it in the correct date format, you can use the TEXT function.
In this example we see that when a reference is made to a date in a formula using a simple cell reference, we get the date converted to a number.
If instead the formula is written using the TEXT function:
="Letter dated, "&TEXT(A2,"mm/dd/yyyy")
. . . the date will be shown in the result of formula.