Question

formula for total gain in db and its absolute value for a signal passing through four cascaded amplifiers

Answer 1

The total gain in dB and its absolute value for a signal passing through four cascaded amplifiers would correspondingly be

$$G_T(\text{dB})=G_1(\text{dB})+G_2(\text{dB})+G_3(\text{dB})+G_4(\text{dB}),\\ G_T(\text{abs})=G_1(\text{abs})·G_2(\text{abs})·G_3(\text{abs})·G_4(\text{abs}).$$