Summary Formula on built in Date Group - How

[hondurab]

I have a report I've grouped by ({Ticket Closed},"monthly&quot, which I am unable to group by in a formula to calculate a summary by month. Is there a way I can still use the system date grouping, and then refer to this grouping in a formula?

Can't group by {Ticket Closed}, as it is not a group, and can't group as shown in first line:

numberVar F:= Average ({@MTTR},({Ticket Closed},"monthly"
numberVar Min := Round ((Remainder (F,1))*60);
If Min = 60 then
numberVar Mins := 0
else
numberVar Mins := Min;
If Min < 60 then
numberVar Hrs := Truncate (F)
else
numberVar Hrs := (Truncate (F)) + 1;
If {?Time Format} = &quot;Time&quot; then
ToText (Hrs,0,&quot;&quot + &quot;:&quot; + ToText (Mins,&quot;00&quot
else
ToText (F,2);

Any suggestions...or group the months from scratch?

Thanks