basically i am trying to set out a timesheet for work , ive managed to get it figure out what hours have been done, - breaks and then convert it to non time format with the following formula :

=(D3-C3+(D3<C3))*24-(F3/60)

this is working fine , BUT i want it to NOT display anything until all cells in the function are filled (D3,C3 and F3)

how on earth do i do this ! ??