Currently if you are constructing a table where you want to perform a calculation on two columns to get an answer in a third you can not (not expected table behavior). So, for example:
Column A - Width, Column B - Length, Column C - Depth. Column D - Vol (m3)
You cannot multiply A*B*C to get D
You can do this outside of a table by creating 3 individual questions and multiplying them in a fourth - but for forms where you want more than one row (i.e. a dynamic table) this is not practicable.
This would have the benefit of reducing form length - making it quicker to design and to use in the field and allow you to perform a wider range of calculations - again making forms simpler and quicker to fill in.