Roman numerals — for parents
Roman numerals are a small but rewarding part of Year-4 maths. They are mostly a reading skill — turning a small set of capital letters into the right number. There is little arithmetic involved, but plenty of careful pattern-recognition. Children usually enjoy them.
What your child should master
- The five symbols used up to 100: I, V, X, L, C (and their values 1, 5, 10, 50, 100).
- Reading any Roman numeral up to 100, including the four subtractive pairs IV, IX, XL, XC.
- Writing any number from 1 to 100 in Roman numerals.
- The "no more than three in a row" rule (no IIII, no XXXX, no CCCC).
- The fact that V, L are never doubled (no VV, no LL).
- Spotting Roman numerals in everyday life: clocks, chapter headings, monarch names, centuries, film credits.
Common mistakes
IIII for 4
Children often write IIII for 4, because four "I" marks looks natural. The standard form is IV.
Help: a clear rule — "never four of the same letter in a row". Whenever the child writes IIII, ask "what's the shorter form?".VL for 45
A creative invention — "V before L means 50 − 5 = 45". But L doesn't accept I or V as subtractive prefixes. Correct form: XLV (40 + 5).
Help: the only subtractive pairs in Year-4 work are IV, IX, XL, XC. Memorise just those four. Any other "subtractive" form is wrong.Adding instead of subtracting at IV / IX
The child reads IV as 5 + 1 = 6 because they sum the letters left to right. The correct read is 5 − 1 = 4 because the smaller I comes before the V.
Help: a clear rule — "smaller before bigger means subtract". Practise on the clock face where IV sits between III and V.Confusing C with 100, M with 1000
Sometimes children swap them (especially if they've seen M = 1000 in passing). In Year 4 we only need C = 100; M is for older years.
Help: stick to I V X L C for now. M and D can wait.Reading right-to-left
The child reads LXX as "XX is 20, then L is 50 → 50 + 20" — accidentally correct, but only by luck. A complicated numeral read right-to-left will fail.
Help: insist on left-to-right reading.Activities at home
Clock-face reading
Look at any analog clock with Roman numeral hours. Ask the child to read each one out loud. Notice IV — does the clock use IV or IIII?
Movie credits
At the end of a film, the year of production is often shown in Roman numerals. Pause and decode together — it's usually a four-digit number with M, but you can practise reading the last two digits up to 99.
Monarch quiz
Print or look up a list of British monarchs (or any country's). Ask: "Henry the what?" while showing Henry VIII. Then make up your own: "If I'm the third Queen Elizabeth, what would I be called?" (Elizabeth III).
Number-to-Roman race
Give a list of decimal numbers 1–100 (a random shuffle of 10 of them). The child writes each as a Roman numeral. Time them; race their own best.
Roman-to-number race
The opposite — a list of 10 Roman numerals, the child writes the decimal. Watch for the subtractive pairs.
Spot the error
Write a list of "Roman numerals" with deliberate mistakes (IIII, VV, VL, XXXXX). The child must spot the wrong ones and correct them.
Why this matters
Roman numerals are partly cultural — they appear on clocks, monuments, books, films. But they also teach an important maths habit: understanding two different positional systems. Our decimal system has place value (the 4 in 47 means forty); Roman numerals don't. Switching between the two trains a flexible numerical mind that will help with everything from fractions to algebra.
Plus, children find them fun. That counts.