A family of Microsoft relational database management systems designed for ease of use.
Create a form (or report) based on the table.
Open it in design view.
Select the text box bound to the field.
Activate the Format tab of the ribbon.
Click Conditional Formatting > New Rule...
Select 'Expression Is' from the first dropdown.
Enter the expression IsNumeric([FieldName]) in the box next to it, where FieldName is the name of the text field.
Click to highlight the B (bold) button.
Click OK.