How do I make a formula automatically pick cells that are not in columns
accordingly whenever new columns are inserted.

E.G 1. Lets assume Col A,B,C is January and E,F,G is February

1 Col A B C E F G H
2 Books Pencil Total Books Pencil Total Grand Total
3 50 10 60 29 11 40 =g3+e3 (100)

Whenever I insert new column (e.g for March) it doesn't automatically affect
my grand total, I have to constantly go through the cells to add the new
Total for march into the grand total. Is there a way (formula) to allow
automatic summing of new grand total once new column for each month are
inserted.

All help and support totally appreciated.

If I have

Col A B C Total
1 5 14 20

whenever I insert new column e.g column D with Value 20, this automatically
adds the new value to the total to make 40 but does not for columns not in
order like E.G 1 above. Can anyone help with the formula to help achieve
this?