6/2(2+1)=? 1 or 9?

    6/2(2+1)           First evaluate the expression in parenthesees.

=  6/2(3)               This can be written like this...

=  \(\frac62(3) \qquad\leftarrow\) Only the thing immediately following the division sign goes in the denominator.

                            Now we can do multiplication/division.

=  3(3)

=  9

6/2(2 + 1) → 6/2*3 → 3*3 → 9

6/(2(2 + 1)) → 6/(2*3) → 6/6 → 1

Very nice way hectictar and Alan!