=B4/(TESTO(C4;"[mm]"))
=TRONCA(C4*24;0)*60+TRONCA(RESTO(C4*24;TRONCA(C4*24))*60)
=B4/(TRONCA(C4*24;0)*60+TRONCA(RESTO(C4*24;TRONCA(C4*24))*60))