Roman Numerals

Instead of using digits, Romans used letters to show numbers. You may have seen the before. This lesson will teach you how to use Roman numerals. Read each slide carefully before going on!

Roman

I II III IV V VI VII VIII IX X 4 5 6 7 8 9 10

English

1 2 3

Roman

XI XII XIII XIV XV XVI XVII XVIII IXX XX 14 15 16 17 18 19 20

English

11 12 13

Roman

XXX XL L LX LXX LXXX XC C D M

English

30 40 50 60 70 80 90 100 500 1000

Roman Numerals

The 4 rules of Roman numerals: 1) Small numbers before large numbers subtract: IV = 4 2) Smaller or equal numbers after large numbers add: VI = 6 L C D M I

Roman

V X 3) You never add more than three of the same number to a larger number: 9 = IX, NOT VIIII

English

1 5 10 50 100 500 1000 4) You never subtract more than one of the same number from a larger number: 8 = VIII, NOT IIX

L C D M I

Roman

V X

Roman Numerals

English

1 5 10 50 100 500 1000 To create big numbers, go from left to right,

doing the last two digits together

:

678:

600: 78: 678: DC LXXVIII DCLXXVIII (500+100) (50+20+8)

2419:

2000: MM 400: CD 19: IXX 2419: MMCDIXX (1000+1000) (500-100) (20-1)

L C D M I

Roman

V X

Roman Numerals

English

1 5 10 50 100 500 1000 Your turn! Turn the following English numbers into Roman numerals in your rough books: 1) 8 2) 28 3) 45 4) 67 5) 82 6) 136 7) 349 8) 698 9) 1,789 10) 2012 Answers are on the next slide.

L C D M I

Roman

V X

Roman Numerals

English

1 5 10 50 100 500 1000 How did you do?

1) VIII 2) XXVIII 3) XLV 4) LXVII 5) LXXXII 6) CXXXVI 7) CCCIL 8) DCXCVIII 9) MDCCLXXXIX 10) MMXII

Roman Numerals

Optime

! You have now taken your first steps towards being a Roman mathematician!

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