I've done my research but I don't have any friend or teacher I can ask to double check my reasoning.

I'm posting this here hoping someone could let me know if what I've done makes sense or if I should review some aspects of it.

I'm trying to make very basic calculations in order to understand the type of power supply I need for my project.

My project is composed of a worm gear motor (12V 3W), a heat sink fan (12V 100W) and an LED (18V 10W).

Overall I believe the Voltage I need is 18 Volts (as each piece will be connected in parallel so don't add up all together like they would if they would be in serie).

In order to find the power in Watts I've divided 113 Watts (all watts added together) by 18 (the highest voltage required in my project).

Overall this is giving me 6.3 Amps.

I came across a fragmented power supply providing 18 Volts and 200 Watts.

I believe such a power supply is providing 11.1 Amps (reached this result by dividing 200/18) and would be suitable for my project.

Am I going in the right direction?

Thanks for your patience.