> Given that they used 42 of them today

20+10+3=33 on the booster, 3+3=6 on the Ship, total 39.

I remember Elon said they want to add 2 engines to the first stage, but that still would be 41. Where's the 42th supposed to be?

I messed up, for some reason I had it in my head that there were 9 on starship, so 33 + 9 = 42.