4.3 ‘Find’ questions
Suppose you have decided to tile the wall using square tiles of side 10 cm. You are proposing to use the tiles across the full 5 metre width of the wall up to a height of 1.8 m.
Find the number of boxes of tiles that you will require to cover the wall if the tiles are sold in boxes of twenty-five. 
The word ‘find’ implies some reasoning is required. Although the following solution contains an error (so it does not get full marks), it is nevertheless worthy of credit. Note how marks are awarded for correct reasoning and justification.
Solution A to Example 14
The error occurs in line 2 where the height of the tiles has been taken as 2 m not 1.8 m. However, credit is gained for those parts that are correct, including correct work following the error.
Solution B to Example 14
By contrast, this correct answer gets only the single final mark – the reasoning and justification marks are forfeited.