Inserting formular in Table

[YMTEO]

I have extracted out some data from the pivot table and now I need to insert
formular for each sale person and each customer (bigger sub group), incase
they want to change the value/ figures.

May I know is there a faster way to do this, in addition to put a farmular
at each subgroup? I have a huge table with many customers, sales man and
product groupings and this is consuming lots of inefficent time

Below is the table format which is looks exactly like pivot table.

Customer Salesman Prodt Data Jan 08 Feb 08 Mar 08
ABABAB HC Prodt A Sales 2,569 2,569 2,569
Vol 107 107 107
Prodt B Sales 1,095 1,247 1,095
Vol 46 52 46
Prodt D Sales 7,440 8,355 7,592
Vol 316 348 316
Prodt F Sales 47 47 47
Vol 2 2 2
HC Sum of Sales 11,302 12,218 11,302
HC Sum of svolume 471 509 471

NK Prodt B Sales 2,590 2,590 2,590
Vol 127 127 127
Prodt C Sales 32,634 18,081 5,591
Vol 2,220 1,230 360
Prodt D Sales 12,288 16,580 15,358
Vol 800 390 360
Prodt E Sales 1,458 8,954 12,288
Vol 90 580 800
Prodt G Sales 32,634 6,615 5,292
Vol 2,220 450 360
NK Sum of Sales 81,604 52,820 41,118
NK Sum of svolume 5,457 2,777 2,007

ABABAB Sum of Sales 92,906 65,037 52,421
ABABAB Sum of svolume 5,928 3,286 2,478

CSCSCS HO Prodt A Sales 9,641 1,128 1,128
Vol 510 60 60
HO Sum of Sales 9,641 1,128 1,128
HO Sum of svolume 510 60 60

JK Prodt B Sales 40,986 40,986 8,197
Vol 2,700 2,700 540
Prodt C Sales 43,056 43,056 43,056
Vol 900 900 900
Prodt D Sales 8,410 2,803 18,221
Vol 720 240 1,560
Prodt E Sales 4,099 4,099 4,099
Vol 270 270 270
JK Sum of Sales 96,550 90,944 73,573
JK Sum of svolume 4,590 4,110 3,270

CSCSCS Sum of Sales 106,191 92,072 74,701
CSCSCS Sum of svolume 5,100 4,170 3,330