Alt text:
For decades I’ve been working off the accumulated rotation from one long afternoon on a merry-go-round when I was eight.
Alt text:
For decades I’ve been working off the accumulated rotation from one long afternoon on a merry-go-round when I was eight.
The mass of the Earth is 5.972 × 1024, so you would need 5.972 × 1020 humans of 100 Kg each all turning in the same direction to make the Earth rotate 1% the other way (so about 597,200,000 trillion humans).
PS: I might be slightly wrong here as rotations have to do with angular momentum which is a bit more complicated than the linear kind because rotational inertia doesn’t depende on mass alone, but the law of conservation of angular momentum does apply.