Percentages of shapes. Estimating percentages. Estimating percentages. Equivalent fractions, decimals and percentages. Table of equivalences. Table of equivalences. Ordering on a number line. Dominoes. Calculating percentages mentally. Some percentages are easy to work out mentally:. 1%.
Some percentages are easy to work out mentally:
Divide by 100
Divide by 10
Divide by 4
Divide by 2
We can use percentages that we know to find other percentages.
Suggest ways to work out:
We can use a unitary method to solve these type of percentage problems. For example,
Christopher’s monthly salary after a 5% pay rise is £1312.50. What was his original salary?
The new salary represents 105% of the original salary.
105% of the original salary = £1312.50
1% of the original salary = £1312.50 ÷ 105
100% of the original salary = £1312.50 ÷ 105 × 100
This method has more steps involved but may be easier to remember.
Percentage increase =
Percentage decrease =
Sometimes, we are given an original value and a new value and we are asked to find the percentage increase or decrease.
We can do this using the following formulae: