I have drawn a sketch of 3-D array to give a rough idea about how it looks like..it consists of many 2-D arrays also referred as Frames.
First see the no. of frames already crossed(given by the 1st dimension).. this means finding out how many elements of frames have already been covered. For that find (no. Of rows * no. Of columns)*no. Of frames given.
After reaching that particular frame, treat the sum as a simple 2-D array sum.
Address = B.A + ((i-LSB)_2D_arrays*no._elements_In_1_2D_Array*instsize + (k-LSB)*no._of_rows*intsize + (j-LSB)*intsize)
The bold parts are the correction. You were almost right :)
Column major order
Address calculation for N-D Array