IPv4 2 transcript

Okay. Uh converting decimal to binary. So there are like we need to learn two types of conversions. One is decimal to binary. Another is binary to decimal. Now the one that we are going to start with is decimal to binary. First of all you need to understand what is a decimal number. A decimal number will be something like 15 16 30 31 32 whatever. Okay. A binary is always it will be 0 1 0 0 then one one one. Okay. So these are the binary numbers.

Now let's take a number. Let's say let's take the number and we want to get the binary of 15. The easiest way to do it I believe but there are multiple ways you can try your own. First of all you need to draw a table. So get a table here and you need to write here remainder then come here okay just draw it depends on the number if the number is it's a large number it's a it's a big number then actually you need a lot of them so 15 I think we don't need more than that so always divide by two then the quotient is 7 and the remainder is 1 2 7 the quotient is three and the remainder is one 2ide by three the quotient is uh the quotient is one and uh the remainder is one as well.

Now if you do again at the end if you divide one by two then the quotient is zero and the remainder is one. Now if you look at here this is the binary but binary is always counted from top from bottom to top okay not from top to bottom. So it will be like um it will be something one one one. So 15 is the decimal. So um 15 will be um you can say uh 15 is the decimal. So you can write something like this. And uh this is the binary.

So you can write something like this. Okay. But 10 and two is not important to write. But um now at least you know u this is how it should be done. Let's do another number which is 16. Let me have a look here because uh you might get confused with here but let's do with 16. 16. So the first thing is to draw the table. I think you don't need more than that. Write here remainder. Okay. So what you need to do here is uh the first thing that you need to do is uh start dividing.

Um so divide always with two. So the remainder uh the quotient is eight. The remainder is zero. Here if you divide 2 by 8 the quotient is four the remainder is zero. Here if you divide two by four the quotient is two and the remainder is zero. Here if you divide 2 by two then the quotient is one and the remainder is zero. Now here is interesting. If you divide one by two um the quotient is zero and the remainder is one.

Okay. Now the most important thing to look at here is how you represent the binary. Okay. The one of the important thing you should continue this one until the quotient until the quotient becomes zero. And it is always counted from bottom to top. Okay? Not from top to bottom. So you have 16 um which is the decimal. the binary will be 1 0 0 0. So this is the binary equivalent for 16. Okay, let us do another one. Let us do another one.

Um uh let us do something. Let's say uh something like uh okay let's do 41. Write here the number 41. First draw the table. Okay. If you divide by two, if you divide by two, it will be um sorry um let's um if you divide 41 by two, the um quotient will be 20. The remainder will be one. If you divide um 2 by 20 the quotient will be 10 and the remainder will be zero. If you divide 2 by 10 the quotient will be five and the remainder will be um zero.

If you divide five by two um then the quotient will be two the remainder will be one. If you divide two by two, the quotient will be zero and the remainder will be wait 40 10 5 2 sorry 52. Yeah, I made a mistake. The remainder um yeah sorry the remainder is one. Okay. Um, give me a second. Yes. So, I got the mistake. If you look at here, so if you divide two by two, um the quotient is one, the rem um uh if you divide two by two, sorry, if you divide um 2 by two, the quotient is one and the remainder is zero.

So if you divide one by two, the like u if you if you do like every time you'll have this, okay, the quotient is zero, but the remainder is one. So um it has to be the quotient has to be zero. So for 41 it will be from bottom to the top it will be 1 0 1 0 0 1. Okay. So yeah. So 41 10 1 0 1 0 0 1 is 2. Okay. But uh 41 this is the binary. Don't worry about 10 and two. Now how can you confirm whether this is the correct?

Let's say let's do a fact check. Okay, let's confirm whether this is a correct or not. So in order to confirm we'll do the opposite converting opposite one. binary to decimal. Okay. Now let's start with one 0 1 0 0 1. Okay. So come here. 1 0 1 0 0 1. Now first of all what you need to do is the first step is to write powers of twos from left to right. So powers of twos from left to right and it starts with zero. So 2 to the^ 0 then 2 to the^ 1 then 2 ^ 2 then 2 to the^ 3 then 2 to the^ 4 then 2 to the^ 5.

Now once you have done the powers of zeros from left to right, what you need to do is convert the powers into uh into actual values. Okay? Like for example, what is the value of 2 to the^ 5? What is the value of 2 to the^ 4? What is the value of 2 to the^ 3? But okay, there is a but here. but only for those powers that corresponds to one. So you will convert the powers into real values but only for those powers that corresponds to one.

So if you look at here this one corresponds to one. This one doesn't correspond to one. This one corresponds to one. Then these they don't correspond this one corresponds to one. So convert the powers. First of all start from left to right. Okay, give power of twos for each of them and then convert to the real values only for those that corresponds to one. Now if you look at here 2 ^ 0 is 1. 2 ^ 3 is you know what is 2 ^ 3 uh 2 to 4 4 to 8 is 8.

Then 2 ^ 5 is 32. Add this number. Okay, add this number 32 + 8 + 1 is equals to 41. Now, if you want to do the fact check with the 41, look at here. You see this is the 41. Fact check with the 41. This is the 41. Now, um you can take any number. You can take any number in the same way uh you can start doing it. Okay. So, this is how uh if someone gives you a number which is a binary number. Okay. And this is how you convert from binary to decimal.

Okay, let's do another one. Now you know IP IP V4 address contains eight bits. So let's try eight bits. 1 2 3 4 5 6 7 8. Okay. Now once you have eight bits the first step is to get the power of twos from left to right. So 2 ^ 0 2 ^ 1 2 ^ 2 ^ 3 then 2 ^ 4 then 2 ^ 5 then 2 ^ 6 then 2 ^ 7. Now look at here there are eight bits since we started from zero. So that is why you stop at seven. Then what you need to do convert the 2 to the powers into real powers only for those that corresponds to 1. 2 ^ 7 is 128 because it is corresponded to one.

So we'll count it. 2 ^ 6 it will be 64 because it corresponds to one. We'll count it. 2 ^ 5 it is 32 because it corresponds to one. Write it down here. 2 ^ 4 is uh 16 because it corresponds to 1. 2 ^ 3 is 8 because it corresponds to one. 2 ^ 2 is 4 because it corresponds to one. 2 ^ 1 is 2 but we will not write it. Why? Because it doesn't corresponds to one. So this is a special one. So it will become zero because it doesn't correspond to one.

Very important. Now 2 to the^ 0 it corresponds to one. So you will write here one. So altogether if you add them 128 + 64 + 32. So if you add them look adding a zero has no values. So you might ask me a question. You are adding here zero but in the previous one you didn't add zero. So what what difference does it make? Like if you add zero here what difference does it make? If you add zero here and another zero here like if you keep on adding them what difference does it make still it's 41 it doesn't make any difference but this is the right way of doing it so it will be all together the binary will be 25 sorry the decimal will be 253 so this is the binary and we convert it to decimal which is 253 okay so uh yes this is the correct way you put zeros as However, if you add zero, it doesn't make any difference.

Okay? Uh it doesn't add any value. So, this is how you convert binary to decimal. Um,