# Archive | WJEC

## Estimating and Approximation

If you don’t have a calculator to hand you are unlikely to be able to work out the value of but a lot of the time this is not necessary. You may only really need to find an answer to the nearest whole number. If this is the case you would actually work out, without […]

An example of a quadratic sequence is: 2, 4, 8, 14, 22 When we find the difference line we obtain 2 4 8 14 22 2 4 6 8 The difference line is not constant so it cannot be an arithmetic sequence. However we can construct a second difference line – the difference between the […]

## Volume

A prism is a shape with a constant cross section, in other words the cross-section looks the same anywhere along the length of the solid (examples: cylinder, cuboid). The volume of a prism = the area of the cross-section × the length. So, for example, the volume of a cylinder area of a triangle = […]

## Finding the Highest Common Factor (HCF) of Two Numbers

The highest common factor is the largest number that divides two number. For example the highest common factor of 6 and 8 is 2 because 2 divides 6 and 2 divides 8 but there is no larger number that divides both 6 and 8. Alternatively we could write down all the factors of 6 in […]

## Mode, Median and Mean

There are three useful measures of average: The Mode is the most common. The Median is found by writing the list in order. For a list of numbers – which we typically have – we write them in order of size from smallest to largest. If the list has an “odd number of numbers” the […]

## Standard Form

A number is expressed in standard form if it is written aswhereis any integer, positive, negative or zero. For example,andandare all written in standard form. We are usually give a number and asked to write it in standard form: Example: Write 342 in standard form Example: Write 0.00045 in standard form Example: Write 3 in […]