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G'day, I'm Dr Peter Price of Classroom Professor. Welcome to this video in the Free Math Worksheet
series. This week the topic is "Roman Numerals". Now maybe that in your curriculum Roman numerals
isn't a topic for instruction in math class, I've done a little bit of looking around and
I can't see it in there. It's certainly a topic I learned at school and I suspect that
you may have learned it when you were at school as well. So this is a topic that maybe of
some interest to you, and to show to your students out of you know, developing a broader
education for them, but it may not be actually a core topic in the curriculum that they learn.
I still think that it's worth teaching there are aspects of our own numbering system or
numeration system which I'll talk about in a moment, which are illustrated by looking
at the way The Romans put together numbers. We also have some context for this, in that
you can still see Roman Numerals today in various places, now in old, on "Old Buildings
and old Clocks" you can still see it. Where I grow up in the UK there are lots and lots
of places where Roman numerals were used on buildings and clocks, but even in Australia
we have buildings that have them. "Page numbers" in the front part of a book, the preface of
a book are often numbered using Roman numerals, "Microsoft Word" interestingly enough still
has that, that option for numbering list and pages and even "Hollywood Movies", I was interested
to see what would happened when we came to the year 2000 and though maybe Hollywood Producers
would you know would stop using Roman numerals but they didn't and they kept on going, so
there are some modern uses. Anyway quick revision, there are 7 symbols in The Roman system and
they have clearly defined values, and they also mirror the first 4 places of our base
10 system by having ones, tens, hundreds and thousands. And of course to make values other
than the ones that have a specific symbol, The Romans would join them together and accumulate
value if you like by adding the individual values. And so students can easily see that
we can make up a value like a child's age might be 12 or something, you can add an X
and two I's and then you have the value 12. The interesting part about that is that there
was also a "Subtractive rule", or is should say there is "Subtractive rule" because we
still use Roman numerals. So that for certain values you would subtract one value from another,
so I'll just add a couple more here, so we've got 5 and 6. Clearly 6 is made up of 5 and
1 but if we put the 1 in front of the 5 then we take it away and make 4, similarly we have
9 as 1 before 10. So there's that extra rule that students need to get used to. I'll just
talk about a couple of, yes values in The Roman system, "I think one like this", here's
the Roman numeral for a year that wasn't so long ago "1999" and you could see each of
the 9s is represented in The Roman system using two characters, so here we have a hundred
in front of a thousand, so that's a hundred less than a thousand, then we have ten less
than a hundred and one less than ten. This of course is a fairly complicated example
so you wouldn't start with this with students but, as I've mentioned before Hollywood movies
have been using Roman numerals to indicate the year of production for some time and so
you'll find movies with that. The following year, was a much more simple symbol in The
Roman system, just "MM -two thousands", because the M represents a thousand we put two of
them to make 2000 and know of course we've moved on and we've got a few more symbols
after that. This illustrates the comparison that I mentioned earlier between The Roman
system and our own base 10 system. Our system of course is a place value system, so each
digit is assigned a value or takes on a value according to the position that it is in, in
the number, so for the number 2000 the 2 represents 2000 because it's in that place. The 3 zeros
don't mean thousand of course they mean "No hundreds, no tens and no ones", forcing if
you like the 2 to be in the thousands place. The Romans didn't have a 0, but they didn't
need a 0, because this M is not the same as a symbol for a hundred, a ten or a one. We
would, they, we would, they would have used different symbols for that, so there's absolutely
no need for zeros and of course they didn't actually have one. Ok so this is just a little
bit of discussion on the Roman system, I hope that your students enjoy playing around with
it if you like, even if it's not a formal part of the curriculum as I've said before
and I hope you find this video useful. So I'll talk to you next time and I'll see you
then.