Index Numbers, Revision Notes

These notes cover Index Numbers, chapter 10 of Form 4 SPM Additional Mathematics. The chapter is built from 2 content standards, listed below with exactly what each expects you to be able to do.

Revise them one standard at a time: understand the idea, learn the method, then practise until the working is automatic. Because SPM marking is analytic, clear, ordered working protects your marks even when a final answer slips, so treat neat layout as part of the revision, not an afterthought.

These formulae are supplied in the exam (they appear on the SPM formula list). You still need to know when and how to use each one:

For each standard above, write out a full worked example from memory, then check it against a correct solution and mark your own working the way an examiner would, a mark for the right method, a mark for correct substitution, a mark for the final answer. Keep a short list of the exact slips you repeat and drill them out.

In Paper 1 the aim is speed and accuracy on routine questions; in Paper 2, the aim is clear, ordered working on longer structured problems. When a chapter feels stuck, that is usually one missing idea rather than the whole topic, a one-to-one teacher can find it in a lesson or two.

• Worked examples (easy)
• Common mistakes to avoid

Index Numbers is chapter 10 of the Form 4 syllabus, and Add Math rewards students who revise in the syllabus order rather than jumping to whatever looks hardest. Almost every chapter leans on the algebra of Form 4, rearranging equations, working with functions, handling indices and surds cleanly, so if any of those feel shaky, an hour spent firming them up will pay back across Index Numbers and everything after it.

When you revise this chapter, keep a running note of any earlier skill you had to look up: that note is a map of the foundations worth repairing. A strong revision plan is not a race through all 2 standards in one sitting; it is short, regular sessions where you revisit a standard, test yourself a few days later, and only move on once you can reproduce the method without the notes in front of you.

Notes and practice take a student a long way, but Index Numbers is one of those chapters where a second pair of eyes makes the difference between "I sort of get it" and "I get it reliably". Working one-to-one, a teacher watches the working as it happens and catches the exact step where a solution goes wrong, a sign dropped here, a condition forgotten there, a formula used in the right place but the wrong way.

That is something a worked answer in a book can never do, because the mistake happens in the doing, not in the reading. Because Index Numbers builds on earlier chapters, a teacher can also spot when the real gap is not in Index Numbers at all but in a Form 4 skill it quietly assumes, and rebuild that first so the new material finally lands.

In every lesson the emphasis is the same: understand the idea, show the method, and make the working clear enough that it earns marks even on a day when the final answer slips. Lessons are one-to-one and online, in English, and the teacher shapes each session around exactly where your child is with Index Numbers, from rebuilding a shaky foundation to sharpening for an A+.

Because the teacher is working with one student and not thirty, the pace is set by understanding rather than by a scheme of work: an idea that clicks in five minutes is not laboured, and one that does not is given the time it needs instead of being left behind for the class to move on.

None of this replaces the notes, examples and practice on this site, it makes them work harder. A student who has read the Index Numbers notes and tried the practice arrives at a lesson with real questions instead of a blank page, and an hour of teaching aimed at those questions is worth far more than an hour spent explaining what a textbook already says.

That is how we like students to use both together: study the material here, notice where it stops making sense, and bring exactly that to a teacher who can close the gap for good.