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The Roman numerals look like this when written in alphabetic order:

C, D, I, L, M, V, X

Use the following clues to fill in the chart to show which numeral has which value.

1 The numeral for 1 came from a tally mark.

2 The numeral for 5 comes from the shape made between the thumb and first finger of a hand.

3 The numeral for 10 comes from two crossed thumbs.

4 The numeral for 100 is the letter that starts the Roman word for hundred.

5 The numeral for 1000 is the letter that starts the Roman word for thousand.

6 The numeral for 500 comes directly after the numeral for 100 in the alphabet.

7 The numeral for 50 comes directly before the numeral for 1000 in the alphabet.

1

5

10

50

100

500

1000

When the Romans invented their numerals (c. 500 BC), they wrote other numbers by writing the numerals next to each other, and adding up their values (the

“Addition Rule”) e.g. MDCCXXIII has value 1000 + 500 + 200 + 20 + 3 = 1723.

What is the value of these Roman numbers?

(a) LXXXVII

(b) CVIIII

(c) MDLXXIIIIII

Writing 9 as IIIIIIIII was very slow and difficult to read, so in the 13 th century, people started using the “Subtraction Rule”. This let them write a small numeral IN

FRONT of a larger one, and its value was subtracted. Now 9 could be written as IX, but only the “ones” (I, X and C) could be subtracted, not the ‘fives” (V, L and D). e.g. MCDXC has the value 1000 + (500-100) + (100-10) = 1490

What is the value of these Roman numbers?

(a) LIX

(b) DXCIV

(c) MCMXLIX

Irene Percival November, 2006