Many students upon reading this question might not realise that it is testing our understanding of the concept on **Highest Common Factor learnt in Secondary 1 Mathematics**.

A floor 6.8m width and 11.05m length is to be paved with equal square tiles. Find the number of largest dimension square tiles that exactly fit the floor?

**Step 1:** I converted the metres into centimetres by multiplying with 100 (1m = 100cm) so that I can work with whole numbers instead of decimals.

6.8m = 680cm

11.05m = 1105cm

**Step 2:** I express each dimension in index notation by prime factorisation method.

**Step 3: **I find the HCF of these two numbers

HCF

This means the largest dimension of square tile will be 0.85m by 0.85m

Number of largest dimension square tiles used

Question of similar nature was asked in the recent year GCE O-Level examination in Paper 1 and many students did not know how to approach the question. I hope you find the explanation clear. It is always recommended to sketch a simple diagram to get your thinking started.