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.