hi my name is kaylee now that we know how to count to 10 in roman numerals
it's time for a challenge let's learn how to count to 39 using roman numerals
we know we can count to 10 using the roman numerals i v and x but did you know that we
can use these same symbols to count all the way up to 39 that's crazy right let's use our rules
to figure out how to do that we're at that tricky problem we always have with fours we know that x
i i i i isn't right how about we think about it as ten plus four do you know the roman numerals
for ten and four yeah x is ten and iv is 4 and since we're adding these together to make 14 we
put the symbol for the smaller number 4 after the symbol for 10. so we can write 14 as x i v sweet
now for fifteen do you know the symbols for ten and five yeah x is ten and v is five remind me
how do we add roman numerals yeah we put the smaller number
after the symbol for the bigger number so 15 is x v now how do we make 16 we just add 1 to 15.
x v i is 16 and 17 we just add 1 to 16 x v i i is 17 and 18 you got it x v i i i
now we're at another tricky number we discovered 18 is x v i i i now what do
we need to know in order to write 19 we know we can't add a fourth i to the end of 18 because
rule number one but we can think of 19 as 10 plus 9. do we know those symbols yes
10 is x and 9 is ix so we can write 19 as x i x now how about twenty
twenty is made up of two tens right we know the symbol for ten so we can just write x x for 20.
now i'm sure you can tell me how to write 21 22 and 23.
that's right we just keep adding those ones x i x x i i and x x i i i
okay we're back to the fours do you remember how we figured out how to write 14
yeah we thought about it as 10 plus 4. so for 24 why don't we think of it as 20 plus 4.
we know 20 and 4 so we can write 24 as xxiv now for 25 we know the symbol for 20 and a symbol for
5 so we can add them together x x is 20 and v is 5. now you tell me how to write 26 27 and 28.
yeah that's right we just add those i's to the end now we're at another tricky number the nines what
do we need to know to be able to write twenty-nine yeah we can think of it as twenty plus nine
what are those symbols x x and i x so we can write x x i x for 29 now how do you think we write 30
well how did we write twenty yeah we added the x's now how many x's make up thirty three so x x x
is thirty now that we know how to write to 30 and all of the rules let's count up to 39 a bit faster
so to count to 33 what do we need to do that's right we just keep adding those i's
x x x i two eyes three i's all the way to 33 now 34 is a tricky one remember we add 30 and
four so x x x i v is 34. now 35 x x x is 30 and v is 5 for 35. now what do we do for 36 37 and 38.
yes we just add those i's to the end
okay so now that final number we're counting to today 39 how should we do that we think 30 plus
9 and we know those symbols are x x x and i x and so we add those together to find x x x i x is 39
you might be wondering why this lesson ends at 39
why not count all the way to 40. we actually need a whole new symbol to even write
40. let's learn how to write bigger numbers in the next lesson in the meantime practice writing and
reading numbers up to 39 in roman numerals have fun and remember to always be clever