How do you add and subtract the binary number system?

You do it exactly like decimal subtraction, and when needed you borrow from the next higher place digit, however remember you borrow 2 everytime and not 10. Some people convert the two binary numbers into decimal, do the subtraction and then convert the result back to binary. Following is an example of binary subtraction.

1001

0110

____

0011

____

I started explaining the borrowing process in Words but it gets confusing. Please relate it to the borrowing process in decimal.