Mastering the Calculation of Percentages

Imagine you're at a store, and you see a sign that says "$25\%$ off all items!". Exciting, right? But how do you figure out exactly what you'll pay? Or suppose you need to calculate what $15\%$ tip to leave at a restaurant. This is where knowing how to calculate percentages of an amount becomes very useful.

 

Understanding Percentages of an Amount

When we calculate a percentage of an amount, we’re finding what part of that amount matches the given percentage. For example, finding $25\%$ of $\pounds 200$ means finding how much $\pounds 200$ would be if we only took $25\%$ of it.

The Formula

To find a percentage of an amount, you can use this simple formula: $$\text{Percentage of an amount} = \left(\frac{\text{percentage}}{100}\right) \times \text{amount}$$

Breaking It Down

1. Turn the percentage into a decimal by dividing by 100.
2. Multiply the decimal by the amount you’re calculating the percentage of.

 

Example:

Find $30\%$ of $\pounds 150$

Solution:

1. Write $30\%$ as a decimal: $$\frac{30}{100} = 0.3$$
2. Multiply by the amount, $\pounds 150$: $$0.3 \times 150 = 45$$

Answer: $\pounds 45$