Which is it,  or ?

They are not the same!

If it's , you write it 4/(5/6).

If it's , you write it (4/5)/6.

By the rules of PE(MD)(AS), if there are
no parentheses you always go left to right 
so 4/5/6 would say to divide the 4 by the
5 first, or 



Put a 1 under the 6:



Invert  and change ÷ to ×



Since 2 will divide into the 4 in the
numerator of the first fraction and
also into the 6 in the denominator
of the second fractions, then do this:



Then multiply the numbers in the numerator and
that will be the numerator of the answer.
Same for the denominator.



Next time use parentheses to group the correct
numbers and operations together.

Edwin