Give this a go....
// form1.page1.subform1.formattedTime::calculate - (FormCalc, client)
var hours = Floor(form1.page1.subform1.timeInMinutes.rawValue / 60)
var minutes = Mod(form1.page1.subform1.timeInMinutes.rawValue,60)
if (minutes < 10) then
minutes = Concat("0",minutes)
endif
$.rawValue = Concat(hours,":",minutes)
Steve