Chapter 21 can be really easy to prepare for before the final exam if the students utilise the appropriate resources. The problem that causes so much apprehension among students is the vastness of the chapter and the number of formulas. If a student takes one day for every topic and practices regularly they will get used to it easily, and after they are done with the whole chapter completely it is highly advisable to go through the ICSE Class 9 Mathematics Revision Notes Chapter 21 for an effective revision.