Building encounters for 1-on-1 games

[Salsmachev]

I like to run games with smaller groups, but I'm trying to figure out how to build encounters for it. I did some basic calculations and, unless I'm mistaken, for a single level one monster to be trivial for one player, that player would have to be level 20. Is that correct? And if so, doesn't that basically mean that you can't do solo adventures without a player having several characters or introducing DMPCs?

[OntosChalmer]

I think your math is slightly off. They'd need to be level 5 for a single level 1 monster to be a trivial encounter.

[Salsmachev]

Oh thank god. I must have gotten a step backwards in my calculation. Thank you!