How are single phase and three phase load amps and load kVA calculated?

"Single phase Amps = (kVA x 1000)/Volts Three phase Amps = (kVA x 1000)/Volts x 1.73 Single phase KVA = (Volts x Amps)/1000 Three phase KVA = (Volts x Amps x 1.73)/1000 "