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Current time:0:00Total duration:4:27

- [Instructor] I remember
when I was in school, I learnt numbers as one,
two, three, and so on, but then when I saw my class board it has class one written on it. You know, first standard, and sometimes we call it
STD, so first standard. And then second standard was
not written as two, but two I's and, you know, second standard. Third standard was written like this, fourth was written like
this, an I and a V, and I did not understand
what was going on. So I asked my teacher, "What are these? "Why are we writing, "why aren't we writing just
second standard like this?" And she said, "Oh, these
that you're used to "they are Hindu Arabic numerals, "the ones that we usually use, "but there are other kinds of numerals "called Roman numerals." And that got me really curious and also a little bit confused. I was asking why are there more than one ways to write numbers and if these are Roman numerals, why don't we use them anymore? And of course what are
they in the first place? And why should I even learn them? That was main question, so why should I know one
more way of writing numbers when I just have one already? And the more I learned about
it I realized that it was learning about Roman
numerals is sort of like visiting a math museum. If you have gone to a
normal or a usual museum you might be used to seeing
dinosaurs or their skeletons. I've seen some fossils as well. And this shows that the
way the world is today is not the way it always was. We had other ways of doing things which we don't do anymore. And I realized that Roman numerals, or learning Roman numerals,
is similar to that. We can go back in time and
see how we used to count and even think about questions like why we don't count like that anymore and is what we're doing
today better and if so, how? So I learnt more about Roman numeral. I had these alphabets
denoting some numbers. Just like in my usual numbers I have one, two, three,
four, or what I call, when I say usual I mean
the Hindu Arabic numerals. I have one, two, three, four, five, six, seven, eight, nine. These are my digits and
using these I can make every other number possible, so these are the digits of
the Hindu Arabic system. Of course, if I also include the pretty important zero to it. So zero to nine make my
Hindu Arabic numerals. Similarly, in the Roman system, they had I, V, X, L, C, D, M. Now these weren't really
the English alphabets that they used, right? We just picked the English alphabets that looked closest to the
symbols that they were using. They were using some symbol
that looked like this, like a stick basically, just a vertical stick to denote one and then they had a symbol V for five, X for 10, L for 50, and C for 100. And that's, this is probably
enough if you know these and if you're interested then there's D and this L-C-D always sticks out to me. D is for 500 and M is for thousand. Now you can notice that using these we don't yet know how to form, how to read or write Roman numerals. All we now know is that these
are the digits that they use. So, in the Hindu Arabic system, maybe I should write Hindu Arabic way out, Hindu Arabic system, how do we write numbers using these. If I want to write 120 then I would take a hundred in my third
digit, as my third digit, then put my two 10s and then zero ones. Then I would call this 120. So I'm using the place value system which you're probably
familiar with right now, the place value system. The Roman numerals did not
have a place value system and they did not even have a
specific alphabet for zero. So there is no zero as you can see here. So they were quite a bit different from our Hindu Arabic numerals, but the interesting thing here is to learn how do we read and write in them and it's not really to
remember to do that, you probably won't be doing it too often. It's just a fun exercise
that we're going to be doing to our own brains.