It would be nice if there was an easier way to calculate fields using a calculation field. In the calculation field, using field ids that could be selected using a token selector, you could create equations such as "item2+item5(item4-item12)". The following operators could be used + - * / and parenthesis for the order of operations. A user would also be able to select how many decimals to show, whether to use a separator, and whether a currency symbol should be shown. When shown on the form, it would not show as a field, but as text that automatically changes when values are entered into the fields used for the equation.