CHW / P1
Early number
Ages 4 to 7, hands on.
Open the syllabusChatswood · Kindergarten to Year 12 and adults · Maths taught live online
Chatswood's Lunar New Year festival has just finished the Year of the Horse, and its organisers say they will see everyone "in February 2027 for Year of the Goat". The animal years come round every 12 years; leap years every 4. So here is a question for a Year 7 student: will a Year of the Goat ever be a leap year? The answer is no, never, and the reason is a lowest common multiple. Because 12 is a multiple of 4, every Goat year leaves the same remainder when divided by 4. The festival's Celebration Day on 13 February 2027 opens a second puzzle about weekdays, worked through below. That is how we teach maths in Chatswood, from Kindergarten counting to HSC Extension 2.
Maths only on this page · Kindergarten to adult · Independent of every Chatswood school and the festival
Maths tutor in Chatswood, in brief
For Chatswood, Modern Age Coders provides live online maths teaching to anyone from 6 to 67: Kindergarten to Year 10 under the NSW syllabus, all four HSC maths courses up to Extension 2, and adult maths. Teaching happens over video at Sydney times, either privately or with up to twenty classmates at the same stage. Our Chatswood example uses lowest common multiples to show why a Year of the Goat is never a leap year. The first lesson is free.
Where Chatswood learners start
Three courses for the most common Chatswood requests; the full list is below.

CHW / 1
Multiples, factors and patterns, the ideas behind every later cycle puzzle.
Open the syllabus →
CHW / 2
Factors and multiples, algebra and geometry, with reasoning written out.
Open the syllabus →
CHW / 3
Functions, calculus and proof for Advanced, Extension 1 and Extension 2.
Open the syllabus →A Chatswood worked example
Two repeating cycles, a 12-year cycle of animal years and a 4-year cycle of leap years, line up in a fixed pattern. The lowest common multiple tells us the pattern.
Chatswood's festival page says "Thank you for a fantastic Year of the Horse celebration. See you in February 2027 for Year of the Goat!"; it also shows pictures from "Chatswood's Year of the Dragon". The Goat years are 2027, 2039, 2051 and so on, 12 apart. Leap years are, almost always, the years divisible by 4. Since LCM(12, 4) = 12, adding 12 never changes a year's remainder on division by 4, so the pattern locks in.
| Animal years | Example years | Remainder when divided by 4 | Leap years? |
|---|---|---|---|
| Dragon | 2024, 2036, 2048 | 0 | Always, until the century rule |
| Horse | 2026, 2038, 2050 | 2 | Never |
| Goat | 2027, 2039, 2051 | 3 | Never |
| Year | Weekday of 13 February | Leap days since the previous Goat year |
|---|---|---|
| 2027 | Saturday | n/a |
| 2039 | Sunday | 3 |
| 2051 | Monday | 3 |
| 2063 | Tuesday | 3 |
| 2075 | Wednesday | 3 |
| 2087 | Thursday | 3 |
| 2099 | Friday | 3 |
| 2111 | Friday | 2 (2100 is not a leap year) |
Twelve years with three leap days are 4,383 days, which is 626 weeks and 1 day. So 13 February slides one weekday later every Goat year, from Saturday in 2027 to Friday in 2099.
Counting "one day per year plus one per leap day" predicts every row correctly until 2099. No calendar software is needed for most of this century.
The year 2100 is divisible by 4 but not by 400, so it is not a leap year. That cycle has only 2 leap days and 4,382 days, exactly 626 weeks, so 2111 is a Friday again.
Multiples, factors, remainders, the lowest common multiple and the greatest common divisor, and reasoning about repeating patterns rather than listing every case.
Years 7 and 8 students handle the leap-year table; senior students can prove that a 12-year shift preserves the remainder modulo 4.
The festival is a real Chatswood event with real dates: Willoughby City Council lists the Chatswood Year of the Horse Festival among its sites. Neither the festival nor the council is connected with us; we only use the published years and dates.
The calendar arithmetic is ours, checked with the standard Gregorian rules.
Sources: Visit Chatswood, Lunar New Year festival and Willoughby City Council, read 14 October 2026. Calendar calculations are our own.
More cycle puzzles
Once students see that repeating cycles meet at the lowest common multiple, they find the pattern everywhere.
| Two cycles | Lengths | They line up again after |
|---|---|---|
| A weekly class and a fortnightly test | 7 days and 14 days | 14 days |
| Buses every 4 minutes and every 6 minutes | 4 and 6 | 12 minutes |
| A 12-year animal cycle and the 7-day week, ignoring leap days | 12 and 7 | 84 (LCM of 12 and 7) |
| Lights flashing every 3, 4 and 5 seconds | 3, 4 and 5 | 60 seconds |
For two numbers, the lowest common multiple times the highest common factor equals the product. For 4 and 6 that is 12 times 2, which equals 24. Students check the rule on several pairs before they trust it.
The calendar puzzle uses the LCM; simplifying fractions uses the HCF. They are two sides of the same factor list.
Real calendars carry exceptions, like the year 2100. Good maths students learn to state the model, use it, and then ask where it stops being true.
That habit matters far beyond calendars, from timetables to physics.
HSC mathematics
NSW students in Years 11 and 12 choose among the Stage 6 mathematics courses published by NESA.
| Course | Suits | More detail |
|---|---|---|
| Mathematics Standard | Practical, applied maths | HSC Standard tutoring |
| Mathematics Advanced | Calculus-based study | HSC Advanced tutoring |
| Mathematics Extension 1 | Strong Advanced students | HSC Extension 1 tutoring |
| Mathematics Extension 2 | Proof and the hardest problems | HSC Extension 2 tutoring |
NESA encourages students to "Look at past HSC exam papers for Mathematics courses with marking guidelines and feedback to help you get ready for your exams."
We use them that way: one paper at a time, marked against the guidelines, with the mistakes turned into the next lesson.
Tutoring improves understanding and exam habits; it cannot promise a band, a mark or an ATAR, and we never suggest otherwise.
Schools set assessment tasks for students to complete themselves, and we keep it that way.
Quoted from the NESA Stage 6 Mathematics page as it read on 14 October 2026.
Kindergarten to Year 10
The calendar puzzle rests on ideas that start in the first years of school and grow every year.
| Years | Idea | A Chatswood-style task |
|---|---|---|
| Kindergarten to 2 | Repeating patterns | Continue a pattern of red and gold lanterns |
| 3 to 6 | Multiples and times tables | Which years between 2024 and 2060 are leap years? |
| 7 and 8 | Factors, multiples, LCM and HCF | When do a 12-year and a 4-year cycle line up? |
| 9 and 10 | Remainders and simple proof | Show that adding 12 keeps the remainder on division by 4 |
Families with OC and selective tests in mind can read OC test maths and selective test mathematical reasoning. Problem solvers may enjoy the Australian Mathematics Competition practice.
Everything else on this page is about ordinary week-to-week maths.
The 2021 Census counted 1,979 Chatswood residents at primary school and 1,592 at secondary school, with 719 in vocational education and 1,836 at university. There were 1,227 residents aged 15 to 19.
Every one of them could join a lesson from home.
Source: ABS, 2021 Census QuickStats, Chatswood, read 14 October 2026.
Sydney time
Lessons follow the NSW terms on the Sydney clock, which moves for daylight saving in October and April.
NSW public schools in the Eastern division start Term 1 on Thursday 28 January 2027, and Term 4 runs from Monday 11 October to Monday 20 December.
Revision blocks before the HSC exams are planned around those dates.
Our teachers work in India, which has no daylight saving. A 6:30pm Chatswood lesson is 2pm for the teacher in winter and 1pm in summer.
Families keep the same lesson time all year.
One teacher, one learner: ideal for a gap, a deadline or a learner who prefers it.
Fifteen to twenty learners at one level, with questions that help everyone.
Each line of reasoning goes up on a shared whiteboard for the teacher to follow.
Source: NSW Department of Education, term dates, read 14 October 2026.
Adult learners
Adults study in their own classes or privately, usually for practical reasons.
Fractions, percentages and ratio, rebuilt calmly with time for every question.
Estimating, checking figures and reading charts, with an eye for numbers that do not add up.
Understanding how schools teach methods now, so homework help agrees with class.
The calendar puzzle is a good first lesson for adults too: it needs only multiples and remainders, and it ends with a genuine surprise in the year 2100.
Progress
A learner moves to the next stage when the skill works on a fresh problem.
| Typically | Stage | Checked by |
|---|---|---|
| Kindergarten to Year 2 | 1. Patterns | Continuing and describing a repeating pattern |
| Years 3 to 6 | 2. Multiples | Listing multiples and spotting common ones |
| Years 7 to 10 | 3. LCM and remainders | Explaining when two cycles line up |
| Years 11 and 12 | 4. Proof | Proving a pattern holds for every case |
Late starters usually need algebra and functions strengthened first; we say how long that should take.
It makes Stage 6 far more manageable.
Adults often enjoy pattern and number puzzles more than they expect.
Adult classes are kept separate from school students.
Course list
By stage. Cards use our international course names; lessons follow the NSW stages and HSC courses.
CHW / P1
Ages 4 to 7, hands on.
Open the syllabusCHW / P2
Each topic in turn.
Open the syllabusCHW / P3
Mental arithmetic, 5 to 10.
Open the syllabusCHW / S1
A fresh start on algebra.
Open the syllabusCHW / S2
Number theory and puzzles.
Open the syllabusCHW / S3
Calendars and patterns in Python.
Open the syllabusCHW / H1
Standard to Extension 2.
Open the syllabusCHW / H2
Data and probability.
Open the syllabusCHW / H3
Beyond the HSC.
Open the syllabusHow it works
Lessons sit at fixed Sydney times, with the October and April clock changes absorbed on our side.
After school
Kindergarten to Year 10.
Evenings
HSC students and adults.
Weekends
Longer lessons by request.
The same teacher week after week.
Brief, honest updates for parents.
Grouped by skill, not just age.
Local dates and data alongside textbook work.
Private lessons can be added before trials.
Learners explain before practising.
Student work
Things made by students who began with maths like this. More in the student labs.

AI and ML
An AI nutrition coach that reads what you eat and works you toward a target.

AI and ML
A chatbot that answers mathematics and programming questions, built and deployed by a student.

AI and ML
An assistant that helps a young person recognise unsafe situations online.

Web app
A weather forecasting site with live conditions for any location.
Fees
Outside India, lessons are billed once a month in US dollars. Joining is free and you can stop whenever a month ends.
Free first class
USD 0
no card required
Group batch
USD 100
a month, billed in US dollars
One to one
USD 150
a month, billed in US dollars
What families say
Families reviewing us on Google, verbatim.
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Chatswood maths questions
Yes. Lessons are online and scheduled on Sydney time, for Kindergarten to Year 12 and adults, as private lessons or level-matched classes.
All four: Standard for applied maths, Advanced for calculus, and Extension 1 and Extension 2 for students who want more depth.
No. Goat years are 12 apart and 12 is a multiple of 4, so every Goat year leaves remainder 3 on division by 4. 2027, 2039 and 2051 are all ordinary years.
The smallest number that is a multiple of two or more numbers. LCM(12, 4) is 12, which is why the animal-year and leap-year cycles line up the same way every time.
A Saturday. In each later Goat year it moves one weekday on, reaching Friday in 2099; because 2100 is not a leap year, it is Friday again in 2111.
No tutor can. We aim for real understanding and tell you frankly how it is going; the band and the ATAR are earned in the exams.
No. Lessons stay at the same Sydney time; we adjust the teacher's schedule.
Yes, in adult classes or one to one.
Under the Gregorian rules, a year divisible by 100 is a leap year only if it is also divisible by 400. 2000 was a leap year; 2100 will not be.
No. It is free; monthly fees after that are shown in the fees panel.
Also on this site
NSW maths pages and our Chatswood coding page.
Proof and complex numbers.
Calculus-based senior maths.
For Year 6 applicants.
Another Sydney suburb page.
The citywide page.
Programming and AI classes.
Start here
Let us know the year level and the topic causing trouble. The free lesson is taught properly, and afterwards you get our honest recommendation.
Background reading: our teaching approach, and online maths lessons across Australia.
WhatsApp us · +91 91233 66161 · connect@modernagecoders.com
Replies come from India, where our teachers are based, so the number has a +91 code. We do not have a Chatswood office. WhatsApp is usually quickest.
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