For the 11+ and Independent School Entrance Exams, pupils need to be able to do the following percentage calculations:

  • Percentages to fractions
  • Percentages to decimals
  • Percentage of an amount
  • Increase/decrease an amount by a certain percentage
  • write one number as a percentage of another number
  • simple reverse percentages

This video shows you how to find a percentage of an amount.

We first work out 10% of the amount – divide by 10

To find 5% : divide the 10% by 2

To find 2 1/2 percent : divide 5%  by 2

To find 1% – divide the amount by 100.




Prior knowledge you need to have in order to work out the size of unknown angles in triangles are:

  • Angles on straight lines add up to 180°
  • Angles around a point add up to 360°
  • When two straight lines cross the opposite angles are equal

This video starts by looking at the properties of the different types of triangles like namely scalene, isosceles, equilateral and right-angled triangle. It then covers the following angle properties:

  • Interior angles of a triangle adds up to 180°
  • Exterior angles of a triangle equals the sum of the opposite interior angles