Topic outline
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In this course you will learn about:- The real number system.
- Natural numbers, whole numbers and integers.
- The highest common factor.
- The lowest common multiple.
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The factors of a number are the numbers you can multiply together to get the number.
Example
\(24=3\times 8\)
So, \(3\) is a factor of \(24\) and \(8\) is a factor of \(24\).
A composite number has more than two factors. \(24\) is a composite number since it has more than two factors.
\(24=1\times 24; 2\times 12; 3\times 8; 6\times 4\)
A prime number has only two factors, \(1\) and itself. For example, \(17=1\times 17\), the only factors of \(17\) are \(1\) and \(17\).
Highest common factor (HCF)
The highest common factor (HCF) (also called the greatest common factor) is the highest common number that divides into two or more numbers.
Factors of \(24\) are {\(1; 2; 3; 4; 6; 8; 12; 24\)}
Factors of \(16\) are {\(1; 2; 4; 8; 16\)}
The intersection of the two sets of factors is {\(1; 2; 4; 8\)} but the highest number in that intersection is \(8\). Therefore, \(8\) is the HCF of \(16\) and \(24\) .
You will use HCFs when you factorise so it is a very important concept to fully understand. Watch the next video to gain a deeper understanding of finding the HCF.