Trick with numbers on strips

Here is a game or trick you can play with your friends/relatives
You need 5 cardboard strips of equal length.Each strip is to be neatly divided into 6 parts.
First part you could name them as A,B,C,D and E,this title appearing at the top of each of these strips.
The remaining parts will carry numbers as shown below-
A         B          C         D         E
8         8           7          3          9
4         3           6          9          7
5         6           1          9          7
7         9           5          8          5
8         7           9          7          6

You can show the strips to your friends/relatives and ask them to place them in any order they like side by side  for example ABCDE,...CEADB or BEACD.
In every case you will be able to tell immediately the total of the 5 numbers appearing in the group of strips
For ABCDE it will be 356194....For CEADB it will be 317593 and for BEACD it will be 367516.
The trick is based on the digits written at the 4th part in each strip namely 5,6,1,9 and 7.The totals in each strip in the remaining parts have been kept at 27.So the totals of the 4 numbers in those strips will be 29997 or 30000 minus 3.So for ABCDE the totals for all the 5 strips will be 30000+56197-3=356194.
Similarly for the arrangement CEADB it will be 30000+17596-3=317593..and for BEACD it will be 30000+67519-3=367516 as mentioned above.
You  can easily tell the total in any other arrangement.In fact 120 arrangements are possible.
You can have even 6 or 7 strips so that  6 digit numbers or 7 digit numbers will be available.
You can even place digits at  another part on each strip like the 3rd part or 5th part instead of the 4th.
You can also make the totals of the digits in remaining parts as 36 instead of 27.In this case you need to add 40000 and deduct 4 to the number appearing on the special part viz the 4th chosen by you.
You can choose the digits in  the other parts in whatever way you like so that the totals are27.