Hi,
This a very interesting question. You should also have added---what language do you count in.
There is a reason for you to think in the language that you think and count in the language that you count in---.
You can make yourself think in a different language---if you are fluent in that language and as long as you are not tired or under duress. If you are under duress and are extremely tired---your thinking nodules will revert back to your mother tongue and you will have to put an effort in thinking in the language other than your mother tongue. Proven under extreme physical torture.
As far as counting---we all revert back to our mother tongue awhen we are counting---that is instantaneous without any effort.
I for myself---switch immediately over to my mother tongue when I start counting---can't or don't want to count in urdu---either it is in english to start with and then switch to my mother tongue immediately, adding, multiplying or subtracting---even though I have lived away from my pakistani brethren for at leasst 25 years, but as far as language is concerned---as tired as I get, the thinking language changes from english / urdu / to my mother tongue---in that sequence.
Now how about another addition---what is the language of your dreams---???