Roman numerals to 100: what children learn
In this matching game, children pair Roman numerals with the numbers they represent. Many rounds include subtractive numerals such as IV, IX, XL and XC, which are the ones children find hardest.
Number-system enrichment, not a Common Core requirement. Explore Roman numerals through 100 alongside world history.
How to play
Pick a card on the left, then the card on the right that matches it. Each game has 6 pairs. Wrong matches are counted as mistakes, and you get three stars for a game with no mistakes.
Step by step
- Learn the symbols. For numbers to 100 you need five symbols: I = 1, V = 5, X = 10, L = 50, C = 100.
- Add when symbols go from large to small. Read from left to right. If each symbol is the same as or smaller than the one before, add them: LXVI = 50 + 10 + 5 + 1 = 66.
- Subtract when a smaller symbol comes first. A smaller symbol before a larger one is subtracted: IV = 4, IX = 9, XL = 40, XC = 90.
- Split long numerals into tens and ones. XCIV = XC (90) + IV (4) = 94. Handle the tens part, then the ones part.
Worked examples
Example 1: XXVII
Working: XX = 20, VII = 7.
Answer: 27
Example 2: XLIX
Working: XL = 40, IX = 9.
Answer: 49
Example 3: LXXXVIII
Working: L = 50, XXX = 30, VIII = 8. This is one of the longest numerals below 100.
Answer: 88
Common mistakes and how to fix them
- Reading IX as 11. Remember: when the smaller symbol comes first, subtract. XI is 11; IX is 9.
- Writing IIII for 4 or XXXX for 40. Standard Roman numerals never use the same symbol four times in a row. Use IV and XL. (Some clocks show IIII, which is a tradition, not the standard form.)
- Thinking there is a Roman numeral for zero. There isn't. This is why the curriculum asks students to learn how zero and place value developed later.
Activities to try at home
- Spot Roman numerals on clocks, watches, film credits and the names of kings and queens.
- Write your age, door number or the date in Roman numerals.
- Make a Roman numeral clock from a paper plate.
Ideas for the classroom
- Compare Roman numerals with our place value system: why is 88 easy to write in digits but long in Roman numerals?
- Research how zero came into use through Indian and Arabic mathematics.
- Do simple calculations in Roman numerals and discuss why they are harder without place value.
Free printable game and worksheet
The free printable starts with a game sheet, such as a color-by-answer picture, an answer maze or a secret-code joke, followed by a worksheet. Both use the same checked questions as the online game, and the answers are on the last page. Print it, or save it as a PDF from your browser’s print menu.
Open the free printable game and worksheet
Frequently asked questions
How do you write 100 in Roman numerals?
C. It comes from the Latin word centum, meaning a hundred.
Why do clocks sometimes show IIII instead of IV?
It is a clockmaking tradition. The standard form is IV, and that is what children are taught in school.
Is this in the US curriculum?
No. Roman numerals are not part of the Common Core, so there is no US equivalent standard.