Albert Teen
powered by
Albert logo


Working with Percentages: Increase and Decrease

Working with Percentages: Increase and Decrease

Working with Percentages: Increase and Decrease

Percentages increase and percentage decrease are useful ways to see how much amounts change over time.

A percentage shows us a proportion of a whole (100%).

What is 100%100\% of 12 cans of cola?

In this lesson, we will look at increasing or decreasing an amount by a percentage. We will need to understand multiplication and division of decimals.

Often, we need to increase or decrease an amount by a percentage, to see how it has changed.

Payrises and VAT are examples of percentage increase. Discounts are examples of percentage decrease.

You buy a car costing £900 and later decide to sell it at a price reduced by 5%. Let's have a go at finding the new price!


Find the percentage of the new price

The old price has been reduced by 5%. Therefore, the new price is 1005=95%100-5=95\% of the old price.


Apply this percentage to the price

95%95\% of the old price is 0.95×900=8550.95 \times 900=855


Nice! 🤟🏼

The new price is £855\pounds855

When you are peeling carrots, you notice that 5% of the mass is lost. How much is left from a bag containing 2.5kg?

Let's see what happens when we need to increase the value by a percentage.

Your bill at a restaurant is £121\pounds121. You want to add a tip of 12%12\%. What is the final total?


We need to increase the price by 12%12\%

Therefore, the new price is 112%112\% of the original.


What is 112%112\% as a decimal?


Multiply £121\pounds121 by 1.121.12 and give your answer to 2 decimal places


The final answer is £135.52\pounds135.52

Nice! We've added on a tip.

You are at a sale and see a jumper with a label that says "Was £50\pounds50 - now reduced by 15%15\%

How much is the jumper now?