Here are the four numbers. Keep them in this order:
18 2 4 3

Here are the tools in your toolbox:
parentheses, exponents (squared and cubed), multiplying, dividing, adding and subtracting.

Using the tools above, insert them between the numbers above to create the given values. Operations
may be used twice if necessary. Not all operations will be used in each expression.

Here is an example:
10 = 18 2 + 4-3

Listed below are the values you need to create
21 =
67 =
-6 =
103 =