A Pie chart is a circular diagram divided into sectors, with the size of each sector representing the magnitude of data it is depicting. Each sector of a pie chart can either be displayed in percentages (note all sectors must add up to 100%) or as an angle (note all sectors must add up to 360o).
Example
The table below lists some of the most popular football clubs and the number of students at a given institution that supports each. Use a Pie chart to represent the information given in the table.
| Football Clubs | Number of Students |
| Chelsea | 50 |
| Manchester United | 200 |
| Barcelona | 350 |
| Real Madrid | 150 |
| Inter Milan | 25 |
| Arsenal | 100 |
| Liverpool | 40 |
| AC Milan | 75 |
The Pie Chart above depicts each sector as percentages. To calculate the percentages for each sector use the formula below:
% of a sector = Number of students x 100
Total number of students
So, to calculate the percentage of Chelsea fans:
% of Chelsea fans = 50 x 100
990
% of Chelsea fans = 5%
For Pie charts which depicts each sector as angles, the angles for each sector is found using the formula below:
Angle of a sector = Number of students x 360
Total number of students
So, to calculate the angle of the Chelsea sector:
Angle of Chelsea sector = 50 x 360
990
Angle of Chelsea sector = 18o
Note: In most cases the questions set on Pie charts require those drawn depicting sectors in percentages.