In how many ways can 12 students be put into groups of 3?

Answer 1

1 way,
4 groups of three

Answer 2

C(12,3) which says 12 choose 3
= 12!/(3!9!) = 220

Good calculators have that function build in
Look for _nC_r

enter 12
2ndF _nC_r
3
=

you should get 220

Answer 3

misread the question.
I gave you "how many different groups of 3 can you choose from 12"

But you want 4 different groups of 3's, right?

that would be C(12,3) x C(9,3) x C(6,3) x C(3,3)
= 220 x 84 x 20 x 1
= 369600