Prime Factorisation: Breaking Numbers Down to Their Basics
Prime factorisation is a crucial mathematical technique that involves decomposing a number into its prime factors. This process is essential for understanding the fundamental building blocks of numbers and has numerous applications in mathematics.
Definition: Prime factorisation is the process of breaking down a number into its prime factors, which when multiplied together, will give the original number.
To perform prime factorisation, one commonly uses the factor tree method. This approach involves systematically breaking down a number into smaller factors until only prime numbers remain.
Vocabulary:
- A factor is a number that divides evenly into another number.
- A prime number is a number that has exactly two factors: 1 and itself.
Example: The number 7 is prime because its only factors are 1 and 7.
The factor tree method for prime factorisation follows these steps:
- Start with the number you want to factorise.
- Find two factors of the number and write them as a multiplication.
- If either factor is not prime, repeat step 2 for that factor.
- Continue this process until all factors are prime numbers.
Highlight: The process of prime factorisation continues until you are left with only prime factors.
Let's look at a detailed example of how to perform prime factorisation using factor tree for the number 840:
- 840 = 42 × 20
- 42 = 2 × 21, 20 = 2 × 10
- 21 = 3 × 7, 10 = 2 × 5
Following this process, we arrive at the prime factorisation of 840:
Example: 840 = 2 × 2 × 2 × 3 × 5 × 7
This can be written more concisely as:
Example: 840 = 2³ × 3 × 5 × 7
Highlight: This final expression, 2³ × 3 × 5 × 7, is called the prime factor decomposition of 840.
Understanding prime factorisation is crucial for various mathematical operations, including:
- Simplifying fractions
- Finding the greatest common factor (GCF)
- Calculating the least common multiple (LCM)
- Solving more complex mathematical problems
By mastering the concept of prime factorisation, students gain a powerful tool for number manipulation and analysis, which forms the foundation for more advanced mathematical concepts.