Solve problems involving simple interest including in financial mathematics
Key Concepts
Use the place value table to illustrate the equivalence between fractions, decimals and percentages.
To calculate a percentage of an amount without calculator students need to be able to calculate 10% of any number by dividing by 10.
To calculate a percentage of an amount with a calculator students should be able to convert percentages to decimals mentally and use the percentage function.
Equivalent ratios are useful for calculating the original amount after a percentage change.
To calculate the multiplier for a percentage change students need to understand 100% as the original amount. E.g., 10% decrease represents 10% less than 100% = 0.9.
Common Misconceptions
Students often consider percentages to be limited to 100%. A key learning point is to understand how percentages can exceed 100%.
Students sometimes confuse 70% with a magnitude of 70 rather than 0.7.
Students can confuse 65% with 1/65rather than 65/100.