Numbers can be broken down and built up in fascinating...
Mathematics2 閲覧数·更新日 Jun 8, 2026·5 ページUnderstanding Factors, Multiples, and Prime Numbers
1 / 5
1
of 5
Understanding the Key Terms
Factors are numbers that divide perfectly into another number with no remainder left over. Think of them as the building blocks hiding inside a number. When you're looking for factors, you're basically asking "what numbers can I multiply together to get this number?"
Multiples work the opposite way - they're what you get when you multiply a number by whole numbers like 1, 2, 3, and so on. It's just like reciting times tables! Multiples keep getting bigger and go on forever.
Prime numbers are the special ones that only have exactly two factors: 1 and themselves. They're like the VIPs of the number world because they can't be broken down any further.
💡 Remember: Factors divide INTO a number, multiples come FROM multiplying a number!
2
of 5
Finding Factors and Multiples
Finding factors is like detective work - you're hunting for pairs of numbers that multiply together to make your target number. Start with 1, then work your way up until you've found all the pairs. For example, with 12: you get 1×12, 2×6, and 3×4, giving you factors of 1, 2, 3, 4, 6, and 12.
Multiples are dead easy - just multiply your number by 1, 2, 3, 4, and keep going. The multiples of 7 are 7, 14, 21, 28, 35, and they continue forever.
Prime numbers have exactly two factors, no more and no less. The number 7 is prime because only 1 and 7 divide into it perfectly. Remember: 1 isn't prime (it only has one factor), and 2 is the only even prime number!
💡 Quick Check: If a number has more than two factors, it's called a composite number!
3
of 5
The Sieve Method and Finding HCF
The Sieve of Eratosthenes is a brilliant way to find all prime numbers up to any limit. You start with a grid of numbers, cross out 1, then systematically eliminate multiples of each prime you find. It's like a mathematical sieve that lets only the primes fall through!
Finding the Highest Common Factor (HCF) involves a simple three-step process. First, list all the factors of both numbers. Then identify which factors appear in both lists. Finally, pick the biggest one from your common factors.
For example, with 18 and 24: the factors of 18 are 1, 2, 3, 6, 9, 18, and the factors of 24 are 1, 2, 3, 4, 6, 8, 12, 24. The common factors are 1, 2, 3, 6, so the HCF is 6.
💡 Pro Tip: The HCF is always smaller than or equal to the smaller of your two numbers!
4
of 5
Finding LCM and Common Mistakes
The Lowest Common Multiple (LCM) is the smallest number that both your original numbers divide into perfectly. List the multiples of each number until you spot the first one that appears in both lists. With 8 and 10: multiples of 8 are 8, 16, 24, 32, 40... and multiples of 10 are 10, 20, 30, 40... so the LCM is 40.
The biggest mistake students make is mixing up factors and multiples! Factors are the few numbers that divide INTO your number, whilst multiples are the many numbers you get FROM multiplying. Think: factors are few, multiples are many.
Another common error is forgetting that 1 isn't a prime number. Prime numbers must have exactly two factors - 1 and themselves. Also, when finding HCF, make sure you list ALL the factors, not just the obvious ones.
💡 Memory Trick: HCF goes down (finding the highest factor), LCM goes up (finding the lowest multiple)!
5
of 5
Quick Test Summary
You've got the tools to tackle any factors, multiples, and primes question now! Factors divide into numbers exactly, multiples come from times tables, and prime numbers only have two factors: 1 and themselves.
For HCF, list all factors for each number, spot the common ones, then pick the biggest. For LCM, list multiples until you find the first match between your numbers.
The key to success is not mixing up factors and multiples - get this right and everything else falls into place. Remember that factors are the building blocks inside numbers, whilst multiples are what you build by multiplying outwards.
💡 Test Success: Practice identifying whether you need factors or multiples first - then the rest becomes straightforward!
そんなこと聞いてくれるのを待ってたよ...
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Mathematics2 閲覧数·更新日 Jun 8, 2026·5 ページUnderstanding Factors, Multiples, and Prime Numbers
Numbers can be broken down and built up in fascinating ways that'll help you tackle fractions and solve complex maths problems. Understanding factors, multiples, and prime numbers is like having a mathematical toolkit that makes everything else easier.
1
of 5
サインアップしてコンテンツを見よう。無料だよ！
- 全ドキュメントへのアクセス
- 成績アップ
- 数百万人の学生と一緒に学習
Understanding the Key Terms
Factors are numbers that divide perfectly into another number with no remainder left over. Think of them as the building blocks hiding inside a number. When you're looking for factors, you're basically asking "what numbers can I multiply together to get this number?"
Multiples work the opposite way - they're what you get when you multiply a number by whole numbers like 1, 2, 3, and so on. It's just like reciting times tables! Multiples keep getting bigger and go on forever.
Prime numbers are the special ones that only have exactly two factors: 1 and themselves. They're like the VIPs of the number world because they can't be broken down any further.
💡 Remember: Factors divide INTO a number, multiples come FROM multiplying a number!
2
of 5サインアップしてコンテンツを見よう。無料だよ！
- 全ドキュメントへのアクセス
- 成績アップ
- 数百万人の学生と一緒に学習
Finding Factors and Multiples
Finding factors is like detective work - you're hunting for pairs of numbers that multiply together to make your target number. Start with 1, then work your way up until you've found all the pairs. For example, with 12: you get 1×12, 2×6, and 3×4, giving you factors of 1, 2, 3, 4, 6, and 12.
Multiples are dead easy - just multiply your number by 1, 2, 3, 4, and keep going. The multiples of 7 are 7, 14, 21, 28, 35, and they continue forever.
Prime numbers have exactly two factors, no more and no less. The number 7 is prime because only 1 and 7 divide into it perfectly. Remember: 1 isn't prime (it only has one factor), and 2 is the only even prime number!
💡 Quick Check: If a number has more than two factors, it's called a composite number!
3
of 5サインアップしてコンテンツを見よう。無料だよ！
- 全ドキュメントへのアクセス
- 成績アップ
- 数百万人の学生と一緒に学習
The Sieve Method and Finding HCF
The Sieve of Eratosthenes is a brilliant way to find all prime numbers up to any limit. You start with a grid of numbers, cross out 1, then systematically eliminate multiples of each prime you find. It's like a mathematical sieve that lets only the primes fall through!
Finding the Highest Common Factor (HCF) involves a simple three-step process. First, list all the factors of both numbers. Then identify which factors appear in both lists. Finally, pick the biggest one from your common factors.
For example, with 18 and 24: the factors of 18 are 1, 2, 3, 6, 9, 18, and the factors of 24 are 1, 2, 3, 4, 6, 8, 12, 24. The common factors are 1, 2, 3, 6, so the HCF is 6.
💡 Pro Tip: The HCF is always smaller than or equal to the smaller of your two numbers!
4
of 5サインアップしてコンテンツを見よう。無料だよ！
- 全ドキュメントへのアクセス
- 成績アップ
- 数百万人の学生と一緒に学習
Finding LCM and Common Mistakes
The Lowest Common Multiple (LCM) is the smallest number that both your original numbers divide into perfectly. List the multiples of each number until you spot the first one that appears in both lists. With 8 and 10: multiples of 8 are 8, 16, 24, 32, 40... and multiples of 10 are 10, 20, 30, 40... so the LCM is 40.
The biggest mistake students make is mixing up factors and multiples! Factors are the few numbers that divide INTO your number, whilst multiples are the many numbers you get FROM multiplying. Think: factors are few, multiples are many.
Another common error is forgetting that 1 isn't a prime number. Prime numbers must have exactly two factors - 1 and themselves. Also, when finding HCF, make sure you list ALL the factors, not just the obvious ones.
💡 Memory Trick: HCF goes down (finding the highest factor), LCM goes up (finding the lowest multiple)!
5
of 5サインアップしてコンテンツを見よう。無料だよ！
- 全ドキュメントへのアクセス
- 成績アップ
- 数百万人の学生と一緒に学習
Quick Test Summary
You've got the tools to tackle any factors, multiples, and primes question now! Factors divide into numbers exactly, multiples come from times tables, and prime numbers only have two factors: 1 and themselves.
For HCF, list all factors for each number, spot the common ones, then pick the biggest. For LCM, list multiples until you find the first match between your numbers.
The key to success is not mixing up factors and multiples - get this right and everything else falls into place. Remember that factors are the building blocks inside numbers, whilst multiples are what you build by multiplying outwards.
💡 Test Success: Practice identifying whether you need factors or multiples first - then the rest becomes straightforward!
そんなこと聞いてくれるのを待ってたよ...
KnowunityのAIコンパニオンとは？
KnowunityのAIコンパニオンは学生向けに設計されたAIツールで、単なる答えを提供するだけではありません。数百万のKnowunityリソースを基に構築され、関連する情報、個別の学習プラン、クイズ、コンテンツをチャット内で直接提供し、あなたの個別の学習過程に適応します。
Knowunityアプリはどこでダウンロードできますか？
Google Play StoreとApple App Storeからアプリをダウンロードできます。
Knowunityは本当に無料ですか？
その通り！学習コンテンツへの無料アクセス、仲間の学生とのつながり、そして即座のサポートを手のひらで楽しもう。
Mathematicsの人気コンテンツ
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探しているものが見つからない？他の教科も見てみよう。
生徒たちが愛用中 — あなたもきっと気に入るはず。
4.6/5App Store
4.7/5Google Play
このアプリはとても使いやすくて、デザインも良いです。今のところ探していたものは全て見つかったし、プレゼン資料からもたくさん学べました！絶対に課題でも使いたいと思います！もちろん、アイデアを得るのにもすごく役立ちます。
Stefan SiOSユーザー
このアプリは本当に素晴らしいです。学習ノートやサポート資料がとても豊富で[...]。例えば、私の苦手科目はフランス語なんですが、このアプリにはサポートオプションがたくさんあります。このアプリのおかげでフランス語が上達しました。誰にでもおすすめしたいです。
Samantha KlichAndroidユーザー
すごい、本当に驚いた。広告で何度も見かけたからアプリを試してみたら、めちゃくちゃ感動した。このアプリは学校で欲しかった「まさにこれ！」って感じのサポートで、特に練習問題や要点まとめみたいな機能がたくさんあって、個人的にすごく助かってる。
AnnaiOSユーザー