Write a numerical expression for the verbal expression: the cube of the quotient of 18 and 6, then find it's value.
what is the best answer for the first part $(18\div6)^{3}$ or $3^3$? and if the second choice is the best one can we call it a numerical expression?
On
I would use your first answer, mostly because it's a literal transcription of the words to symbols. As a side note, you're welcome to use $\div$, but as far as I can tell it is not used anywhere except grade school, at least in the US. For all I know, you are in grade school, in which case it's completely appropriate.
Let's remember the definition of a numerical expression: A numerical expression is an expression composed of only numbers and operational symbols. Both answers you have provided are not only equal to each other, but are both numerical expressions. However, the "best" answer for the question you were provided is $(18 \div 6)^3$, since that is representing what the question is. But, by the order of operations, it is equal to $3^3$. Bottom line: first answer is best, but both answers are numerical expressions.