Hi, I am having trouble understanding the mathematical part behind subtractors and adders.

Could anyone please explain it to me?

Here is an example:

A1A2A3A4​

- B1B2B3B4​

---------​

Y1Y2Y3Y4Y5​

 

Try the material in our Ebook - http://www.allaboutcircuits.com/vol_4/chpt_2/index.html

In decimal, 1 + 1 = 2

In binary, 1 + 1 = 10