Best Buy Questions

Best buy questions involve deciding which product works out cheapest. As the products are given in differing quantities we need to do some maths before we can compare them.

We either need to make the quantities the same or the cost the same. For most questions it is normally easiest to make the quantities the same.

One option is to find the cost of one of the products using the unitary method (divide the cost by however many you have).

The other option is to find a common multiple of the products. In the example question we have the price of 4 toilet rolls and the price of 9 toilet rolls. We can compare them by finding a common multiple of 4 and 9 (36 rolls).