Jst wntd to throw out that technically a mclass chrctr can learn spells based on their multiclass spell slots, as the mclass rules tell you to refer to ur single class for spells knwn and prep, those classes say u can choose spells of any level you have slots 2/2 so technically you could take a 10 Cleric/ 2nd level in Sorc and learn a spell of 6th level from the sorc list. Same with prepped spells, you can only prep a small # but they can be any level you have slots. Probably not intended but wording wise it seems possible.
— KekDaSnek (@KekTheSnek) December 10, 2017
Take another look at the rule. When figuring out spells known, you pretend you’re not a multiclass character. You look only at what’s in the class’s description, including its table.
— Jeremy Crawford (@JeremyECrawford) December 10, 2017