Binary addition and subtraction

Introduction

Placeholder for if there is anything to learn about this

Addition

Just line them up and do the work

 1111 
  101101
+ 111101
  ------
 1101010

I guess the only thing which is a trick, is that three 1's is 1 carry 1.

Subtraction

So this is something I perhaps did not notice that borrowing is done in 2's as each column has 2 values. So

  2 
 100
- 10
 ---
  10

This perhaps is shown more clear when we borrow over two columns

   1 
   2
  100 
-   1
  ---
   11

Hopefully the picture paints a thousand words

When we borrow we always borrow two.