In this case, are "mix up" and "shuffle" synonyms?:
"I'll shuffle/mix up the cards".
Thank you 5.
When could we say "mix up the cards"?
If you took two packs of cards, you could mix them up, or if you moved them out of sequence when you weren't supposed to.
If the standard methods of shuffling are not appropriate, such as if you were doing a card trick with just a few cards you could say 'Mix them up so I've no idea what order they're in'.