How to Determine CR for Encounters

[MrFrodo17]

I've read through the part of the Game Mastering chapter dealing with setting CR and giving XP, and I'm honestly confused. I'm a new GM, and I'm coming to Starfinder via 4th edition and 5th edition D&D, so that might explain my confusion with CR. My biggest question is this: is CR summed and divided like APL?

For example, if I have 4 1st-level PC's, to determine their APL, I add together their levels to get 4, then divide by 4. Bam, their APL is 1. Let's say I want them to fight a CR 1 encounter. Would I just throw one CR 1 enemy against them? Or would I take 4 CR 1 enemies and similarly divide their CR by 4 to get a CR of 1?

I'm also a bit confused about the "CR Equivalencies" table and how it relates to creatures with CR in fractions. For example, let's say I wanted the party to face two mercenaries, each with CR 1/2. Would their CR together be CR 1? Or would be CR 2-1/2, since the table says two of the same creatures' CR equals their CR + 2?

I apologize for these noobish questions, but I would definitely appreciate any help!

[Goddity]

Yeah, CR is confusing. I think there has to be a better way to do it, but can't think of one.

Question 1: One CR 1 enemy is a CR 1 encounter. Four CR 1 enemies is a CR 5 encounter. Just throw the one at them.

Question 2: My opinion is that the CR Equivalencies table causes more trouble than it helps. So break it down like this: two CR 1/2 mercenaries. According to table 11-3, CR 1/2 = 200 total xp. Since you have two of them, you add the xp getting 400. Looking at the table again, this is a 400 xp = CR 1 encounter. Therefore I think I would conclude that table 11-2 only applies for CRs greater than 1 and should just be ignored in favour of doing it by hand anyway.

Does that help?

[MrFrodo17]

That does help, thank you!