Katie and Ben visit the high street to see what the sales have to offer. They find that percentages are used to express discounts, and set off on a 'discount dash' to see who can scoop the best bargain. Each has £75 and half an hour to choose at least three items, with the aim of making the greatest saving on their purchases.

00.42-02.45

Ben and Katie dash round the shops, stopping to highlight some of their finds. Katie shows how to estimate a 15% discount in her head.

02.45-04.38

Time to compare purchases. Each item they have bought shows the original price, the percentage discount and the sale price. Katie is confirmed as the 'bargain bagger', saving £45 compared with Ben's £40.

04.38-06.08

While Katie goes for some more 'retail therapy', Ben shows how to calculate Katie's total saving as a percentage of the original price. He introduces the formula:

(percentage change) = ^(change) / _(original) x 100%

Katie points out that exam questions cover percentage increase as well, and that they are not always about prices and shopping.

06.08-09.06

The 'Tick or Trash' sequence features the calculation of a percentage increase. Ben's error leads to further discussion of the percentage-change formula.

09.06-11.08

In a supermarket, offers like '3 for the price of 2' are described using percentages. The manager explains the types of offers that are typically seen (including the favourite BOGOF - 'Buy One, Get One Free'). We see how to use the percentage-change formula to compare two deals.

11.08-11.53

Ben and Katie set off to find as many 'extra free' deals as they can.

11.53-13.14

Katie explains how you can work out how much more of a product you are getting for your money. Taking a packet of biscuits as an example, she works out the size of the normal packet and hence the number of free biscuits in the special-offer pack. Ben poses a similar question with a bottle of shampoo.

13.14-end

Katie discovers Ben trying to load the checkout with the extra free items - and takes charge! Ben concludes that 'You don't get nothing for free these days!'