Issues in computing indexation allowance

Hi, when I am trying the BBP practice kit questions I found out a issue in computation.

For example:
Question 162 involves in indexation allowance, the answer compute it as below:
Indexation allowance
(263.0-215.1)/215.1X£8000=£1781

Although I used the same equation to compute, I firstly got the result of the part
(263.0-215.1)/215.1=0.223
which makes the indexation allowance £1784

Therefore different from the standard answer.

So which method should I use in exam?

Thanks.