Roman numerals to 1000

Roman numerals are a numeral system which was used in Ancient Rome.

It uses letters instead of numbers to represent values.

You may have seen Roman numerals on clocks and on TV or film credits.

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There are seven Roman numerals and each one has a different value.

The Romans used these seven numerals to create all the other values.

This is similar to our number system; we use 10 different values (0-9) to make all the other numbers.

Roman numerals are usually written as capital letters.

You usually only write a maximum of three of the same numeral in a row.

There is no zero in the Roman numeral system, so they did not use zero as a placeholder like we do.

This is the number 56 in Roman numerals:

Reading Roman numerals

When reading a Roman numeral, you read from left to right.

If all the numerals are in size order, starting with the largest, we add all the values together.

In this example, the numerals are in size order because X is greater than I.

You can see 3 tens and 2 ones. When you add them together it equals 32.

If all of the numerals are not in size order, starting with the largest, then you need to subtract.

In this example, the numerals are not in size order because X is less than C.

This means you need to subtract X from C, before you add the values.

100 – 10 = 90

XC = 90

Now you can add the other values.

90 + 5 + 1 = 96

XCVI = 96

Writing Roman numerals

Can you work out how to write 77 in Roman numerals?

First, it helps to partition the number into tens and ones.

Now you can convert.

You cannot write X seven times, because you usually only write a maximum of three of the same numeral in a row.

So you need to break it down further and think about the Roman numerals you can choose from.

70 can be partitioned into 50 and two 10s.

7 can be partitioned further into 5 and two 1s.

These values have Roman numerals.

Therefore, 77 is written as LXXVII in Roman numerals.

Example 2