simplifying algebraic expressions

Question

From a textbook: $km \times mn \times nk$

Answer says: $k^2m^2n^2$, but why can't that be simplified further to $(kmn)^2$?

$3pq^2r \times 6p^2qr \times 9pqr^2$

Answer says: $162p^4q^4r^4$, but why can't that be simplified further to $162(pqr)^4$?

Answer 1

it is $$km\cdot mk\cdot nk=k\cdot k\cdot m\cdot m\cdot n\cdot n=k^2m^2n^2=(kmn)^2$$ and for your second question: $$3\cdot 6\cdot 9\cdot p\cdot p^2\cdot p\cdot q^2\cdot q\cdot q\cdot r\cdot r\cdot r^2=...$$?$$