Binary Addition and 2's Complement tutorial

This video discusses binary addition and subtraction and the 2's complement of a binary number.
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[Xlmk]

Why is a 30 min video on youtube better than many professors in Universities. I'm pretty slow, but after watching this I can finally understand the logic behind subtraction in CPUs.

[fadyfarouk]

I love how direct and simple this video is. It has helped me a lot, thanks a million!

[Ankit-ywcq]

I need a teacher like you I was so confused in this topic

[h.cazador]

You're an amazing teacher! Such a thorough and detailed lesson. Thank you so much :)

[sapn]

One thing is still not understood, is there any explanation as to why we discard the sign bits, how will the computer program decide when to keep it and when to discard it?

[katyblue]

you make everything so simple and easy !!!!, I love this tutorial !

[felipejordao]

I finally understood this topic.You answered all my questions.Nice job!!!

[gouthamtadali]

Please anyone clarify this for me;
8 = 1000
If we want signed representation 4 bits are not enough.
so taking 5 bits
+8 = 01000
To represent -8 in 2's form; take 1's of +8 and add 1 to LSB. Is this right?
So, 10111+1 = 11000
Isn't this -8 in 2's form?

[charlinemontial]

When you say, about the 2's, that we have to add one, I would have precised that you add one to the LSB :) (Least significant bit)

[santiagorivera]

Two questions:
1. Why are you able to discard the bit all the way to the left of the result if there is a carry-over at the end of the addition?
2. What happens if you add 9+8? You would get a number higher than the highest number you can represent using this 5-bit system. As a matter of fact, what if you add any a+b that would give you a sum larger than the highest number that can be represented using this 5-bit system in the problem?

[geardoarfanny]

Damn man, you are so smart. You really helped me. Thanks a lot broo 👍👏🔝

[milajoy]

Thank you so very much! So clear and easy to understand 🙏🏻🙏🏻🙏🏻

[laralara]

you made it so simple, I understood more in this video than 15 and so lectures...thanks a lot

[ruotongli]

I instantly understand all concepts. Thx a lot !

[PhilipMachanick]

Something not explained clearly is that these representations only work if you fix the number of bits and pad a positive number to the left to make up the width of the number. Complementing is not usually done by treating the sign bit as separate though it works this way. While it is true that you can subtract by negating and adding, a subtractor is a very simple circuit so most real machines have subtract operations. The real value of 2‘s complement is that addition and subtraction work the same way with positives and negatives, with a very simple overflow check (if exclusive or of the carry in and carry out is 1, you have an overflow). With signed magnitude (“true magnitude”) you need to handle negative numbers differently. 1’s complement has the oddity of 2 ways to represent zero. Flip all the bits of zero and you get a word of all 1s. Minus zero makes no sense mathematically. 2‘s complement only has 1 representation of zero: negate it by flipping the 0s and add 1, and you get back to all zeros.

[kevinjosephjr]

are you a teacher? I hope so, you do a great job at giving instructions, I was struggling learning this from the book, maybe you should write a textbook someday, or maybe a professor at a university somewhere.
Thanks for the video,
-K

[armsvelt]

Very nice video. Well explained, you took your time, worth watching every minute.
Quick note: You only have amazon affiliate links to .com amazon, would it be possible to set it up according to the geo location of the user?

[LonleyGuns]

There is a part of this video not clear for me (22:25). When we convert 9 into 2's form we get 10111. With 4, the result is 1100. When you sum the numbers, there is another 1 before 4. If 9 -> 10111 (-9), why 4 ->11100 ? I thought that if we want the same bit sizes, we expand with 0, not 1.

[preethumarygeorge]

I loved this tutorial...everything was soo clear

[vishnupatil]

Such a good explanation on a topic like this. Great