I have a field that is declared as a varchar that is suppose to hold time spent working on a project. The field is filled with data like 05:00:00 or 36:00:00. I have been requested to add up those hours and place them into a field that is declared as a decimal data type. I have tried using the CAST function to convert it to a decimal but it has an error converting the format. Is there any way to convert the field into a format that I can run calculations on.