Iterative division for HCF

How to write this in exams

1. 1

   Start with the exact idea

   Iterative division for HCF is a step-by-step method where the larger number is divided by the smaller number, then the divisor and remainder are used again until the remainder becomes 0. The last non-zero remainder is the HCF.

2. 2

   Then show how to use it

   1. Divide the larger number by the smaller number. 2. Write the remainder. 3. Replace the pair by divisor and remainder. 4. Continue until remainder is 0. 5. The last non-zero remainder is the HCF.

3. 3

   Add one concrete example

   For 252 and 198: 252 = 198 x 1 + 54, 198 = 54 x 3 + 36, 54 = 36 x 1 + 18, 36 = 18 x 2 + 0. So the HCF is 18.

4. 4

   Avoid this incomplete answer

   Taking 36 as the HCF in the worked example is wrong because 36 is not the last non-zero remainder.