Math // Number Representation & Place Value
Number Words to 100
Read and write numbers to at least 100 in words
Quick check
Can the learner write 'seventy-four' or 'one hundred and three' as number words — and read them correctly when they appear in a book or on a sign?
Ask this to see whether the topic is secure.
Topic // Mastery
What mastery looks like
- Read 'fifty-seven' and write the numeral 57
- Write 'eighty-three' when shown the numeral 83
- Read and write all decade words (twenty, thirty … ninety) correctly
Topic // Map
Where this fits
- RequiredMust come first
- HelpfulHelps, but not essential
Before this
2 topics- Number Words to TwentyRequired
Number Representation & Place Value // Ages 5 to 6
Writing number words to 100 extends from writing number words to 20
Number Representation & Place Value // Ages 5 to 6
Writing number words to 100 requires reading the corresponding numerals
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Number Words to 100
Ages 6 to 7 // Language
Leads to
1 topicNumber Representation & Place Value // Ages 7 to 8
Reading/writing to 1000 extends reading/writing to 100
Topic // Research-informed
Teaching notes
From the Marble Skill Taxonomy. These notes have not been validated in classrooms, so treat them as a starting point for your own judgement.
The approach
For ages 6–7: reading and writing numbers to at least 100 in words, extending from number words to twenty into the decade words (twenty, thirty … ninety) and two-word hyphenated compounds (fifty-seven). The central work is mapping word ↔ numeral ↔ quantity, learning commonly misspelled decade words (forty drops the u of four; ninety keeps the e of nine), fixing the hyphen, and untangling the sound-alike '-teen'/'-ty' pairs (fifteen/fifty, thirteen/thirty). Above twenty the English words follow a regular tens-first pattern (decade word, then ones word), a useful contrast with the teens, although some decade stems (twenty, thirty, fifty, forty) are spelled irregularly.
Common misconceptions
- Confusing '-teen' and '-ty' words by sound and spelling (fifteen vs fifty, thirteen vs thirty).
- Misspelling irregular decades (forty as 'fourty', ninety as 'ninty').
- Omitting the hyphen or writing compounds as one/many words incorrectly.
- Transposing compound numbers back to numerals (writing 'forty-two' as 24) — carrying over the teen ones-first habit.
- Writing decade words with extra zeros from the spoken parts (fifty-seven → 507).
Useful representations
- Decade-word chart (20–90) linked to the tens digit and to bundles of tens.
- Word-building frame: [decade word] + [ones word] → compound (sixty + four → sixty-four) beside 64.
- Triple-match cards: numeral ↔ word ↔ quantity/number-line position.
- Sound-alike contrast pairs (thirteen|thirty, fifteen|fifty) each with a set/numeral.
Teaching practices
- Teach the DECADE words as a set (twenty…ninety) and their link to the tens digit, then the regular compound rule 'decade-word + ones-word' (sixty-four) — above twenty the words are tens-first and regular, a helpful contrast with the teens.
- Drill the sound-alike traps directly: thirteen/thirty, fifteen/fifty, etc. — pair each with its numeral and a quantity so meaning disambiguates the near-identical words.
- Always connect word ↔ numeral ↔ quantity (read 'seventy-two' → write 72 → show ~72 on a line) so the words carry meaning, not just spelling.
- Address orthography explicitly: the hyphen in compounds (forty-five), the tricky spellings (forty not fourty, ninety), coordinating with spelling/handwriting teaching.
- Practise both directions and across decade boundaries (seventy-nine → eighty) to cement the compound structure.
Activities to try
- 1
Build compound number words from decade + ones parts
Why it works: For numbers from21 to99 with a nonzero ones digit, the English word is a tens-first compound, such as sixty-four. Exact tens use the decade word alone, and100 is one hundred; connect each form to its numeral and quantity.
- Choose a decade-word part (e.g. 'sixty') and a ones-word part (e.g. 'four') and join them into the compound word 'sixty-four', writing it with the hyphen.
- Write the numeral64 beside sixty-four and locate it on a0–100 line. Optionally join on-screen tens and ones word tiles so the compound immediately links to its numeral and line position, with a reverse round asking the learner to assemble or spell the word for83.
- Work the reverse direction: shown the numeral 83, say and then correctly spell the word 'eighty-three'.
- Write seventy-eight, seventy-nine, eighty, eighty-one, then ninety-nine and one hundred. Notice when a decade changes, when a hyphenated compound is used, and how100 is written.
- 2
Sound-alike contrast: '-teen' versus '-ty'
Why it works: The '-ty' word names a number of tens (fifty = 5 tens) while the '-teen' word is a teen (fifteen = 1 ten and 5); linking each to a quantity removes the guesswork from the near-identical sounds.
- Take a minimal pair such as fifteen/fifty and read both aloud, stressing the ending (-teen vs -ty).
- Beside each word, write its numeral (fifteen = 15, fifty = 50) and show a matching quantity or base-ten model (fifteen = 1 ten and 5 ones; fifty = 5 tens).
- Repeat with thirteen/thirty and other pairs, each time pairing word, numeral and quantity so meaning separates the near-identical sounds.
- Answer a quick 'fifteen or fifty?' decision with the set of objects visible, choosing by quantity rather than guessing.
- 3
Use number words in a real read-and-write task
Why it works: A learner who has the system can move fluently in both directions — word to numeral and numeral to word — without concatenating the spoken parts or confusing teen and decade words.
- Given a label showing the numeral 76, write the words for a new label a customer could read ('seventy-six'), ordered correctly and hyphenated.
- Given the word 'eighty-three' on a card, read it and write the numeral (83).
- Check a friend's work: they wrote 803 for 'eighty-three' — decide whether it is right and explain what went wrong.
- Compare 40 and 14 (and 'ninety' vs 'nineteen'): read each aloud and write each the other way to confirm you can move both directions.
Topic // Standards
Curriculum standards
- The national curriculum in England: Key stages 1 and 2 framework document
- Maths/Y2/NPV/5
Math // Number Representation & Place Value
More in Number Representation & Place Value
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- The two digits of a two-digit numberAges 6 to 7ConceptUnderstand that the two digits of a two-digit number represent amounts of tens and ones
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- 10 More or 10 LessAges 6 to 7MethodMentally find 10 more or 10 less than a given two-digit number without counting
- Place value understanding and number factsAges 6 to 7Thinking skillUse place value understanding and number facts to solve problems
- The multiples of 10Ages 6 to 7ConceptUnderstand that the multiples of 10 (10, 20, 30 … 90) represent one to nine tens and 0 ones
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