Message: Is there a formula in MS Excel that will calculate times, say in 5 or 10 minute increments?  For instance, I am working with a schedule for classroom teachers to know when to bring their classes to lunch.  If I were using simple numbers instead of times, and a2 was 900 I could use =a2 10 to get 910, but I need it to be a time. The pull down feature won't work in this instance, because there is not a consistant pattern (i.e. some classes are 5 minutes later, some 10, and there might be two at one time, three at another, or even one by itself). The use of a formula would allow me to move the entire schedule earlier or later by merely changing the first time in the list.  Any suggestions?  Thanks!