How do I know the voltage and wattage requirements for my notebook?

There are two ways to know the NB wattage, which shows the voltage-V & current-I

(1) To check the label on notebook bottom.

(2) To check the label on original adapter

The label shows,

The wattage
Voltage(V) x Current (A) = NB Wattage

19V x 4.74A = 90W

19V x 3.42A = 65W