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Prime Time · Find common multiples · 3:41

You'll learn: Use a short list to solve a repeated-event problem

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Find the first meeting and later meetings

3:41

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Find the first meeting and later meetings

You'll learn: Use a short list to solve a repeated-event problem

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Find common multiples

1

When do repeated steps meet
3:40
When do repeated steps meet
You'll learn: Find common positive multiples

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Distinguish primes composites and one

2

Prime numbers have exactly two factors
3:36
Prime numbers have exactly two factors
You'll learn: Distinguish prime and composite numbers
Why one is different and two is prime
3:34
Why one is different and two is prime
You'll learn: Correct common classification mistakes

Next topic

Identify primes systematically

2

Sift a number grid for primes
3:33
Sift a number grid for primes
You'll learn: Use a systematic sieve on a finite grid
Check a proposed prime carefully
3:30
Check a proposed prime carefully
You'll learn: Use factors and counterexamples instead of appearance

Next topic

Understand coprime numbers

3

Coprime describes a pair
3:26
Coprime describes a pair
You'll learn: Recognise two numbers sharing only factor one
Composite numbers can be coprime
3:38
Composite numbers can be coprime
You'll learn: Distinguish coprime pairs from pairs of primes
Coprime steps make a thread pattern
3:28
Coprime steps make a thread pattern
You'll learn: Explore repeated jumps around a finite peg circle

Next topic

Build and interpret prime factorisation

4

Break a number into prime building blocks
3:27
Break a number into prime building blocks
You'll learn: Continue splitting until every factor is prime
Different trees give the same prime collection
3:47
Different trees give the same prime collection
You'll learn: Check factorisation by multiplying back
Use prime tiles to check coprimality
3:42
Use prime tiles to check coprimality
You'll learn: Find shared prime factors systematically
Use prime tiles to check divisibility
3:42
Use prime tiles to check divisibility
You'll learn: Check that the divisor’s factors are all available

Next topic

Use and explain supported divisibility tests

3

Divisibility by two five and ten
3:35
Divisibility by two five and ten
You'll learn: Connect last-digit rules to place-value groups
Why the last two digits decide divisibility by four
3:38
Why the last two digits decide divisibility by four
You'll learn: Use hundreds as complete groups of four
Why the last three digits decide divisibility by eight
3:47
Why the last three digits decide divisibility by eight
You'll learn: Use thousands as complete groups of eight