Macro to change month's number in a formula

Hi,
I have 2 columns in a a sheet, some cells in the second (not all cells) contains the current month's number (it comes after the multiplication sign in those formulas).
i need a macro that allows me automatically to advance the month's number each month in this formula (just the month's number), if it's 1 advance to 2, 2 to 3, 12 to 1 etc....
see a example of my formulas below, the formulas are in colomn B, the month number is whatever comes after * (multiplication sign).
example:
5500/11*12
12000*12+55000
=A2/11*12+55000
i'm new in macros, i really appreciate any ideas (i'm using excel 97).
thanks.

thanks Karim for your help, but it's not exactly what i want.
i wanna keep these formulas as they are till i change them some day during the month, i don't want excel to automatically change them at the begining of the month, but when i wanna change them, and so on each month.

or eventually put your formula Carim (Month(today())), but is there anyway to not activate the changes inside the cells till i want that.
is it feasable what i'm saying or it's just dreaming.
thanks for any help!

the triggering factor it's when i wanna change them. it's a sheet that i dive it monthly to the direction, durind the month for the month before.
example i'm in mid february, i wanna change 12 (dec.) to 1 (jan.), in all the cells that contains 12 in that column (B).

i guess it might help, but i'm not familiar with macros, so i copied and pasted your code it gave error 1004, method range of object global failed.
what did i have to put into my range? then is there anyway to not doing any changes to the macros every month meaning including a part that advances whatever i wanna change month by month.
thanks carim for your help

thanks for your help Carim,
we're almost done, but just a tiny little thing, it's i wanna just change the number that comes after the multiplication sign in case we have the same number twice or more in the same cell.
example: 52000/12*12+15000, just change the 12 that's after *.

it didn't work out Carim,
examples:for: 600000/12*12 it gave *11*11
for: 97000/12*12+55100 it gave *11*11+55100
for: 12000/12*12 it gave *11*11*11

it' still the same result Carim

it works Carim.
Thanks a lot for your help, and thanks for everybody in this forum.