Absolute value of directed numbers

2026-11-03Numbers & Estimation Ms Lam

Read |a| as distance from zero and simplify expressions with absolute values.

Key formulas

|a| \ge 0

|-a| = |a|

What this lesson covers

This lesson builds Secondary 2–3 skill in absolute value. Read the key formulas, study the worked example, then attempt the written practice and the four-question MCQ review.

Method

Write every step. Name the rule you use (absolute value) before substituting numbers. Keep units and signs visible until the final sentence.

Common mistakes

Students often rush the sign, use the wrong percentage base, or cancel terms instead of factors. Pause after each line and ask whether the step is reversible.

Exam habit

Underline the question verb (simplify, solve, factorise, find). Box the final answer and, where sensible, substitute back for a quick check.

Worked example

Worked example — absolute value

Problem. Apply the method for absolute value with the numbers 5 and 4.

Solution. Identify the rule for absolute value. Substitute 5 and 4 carefully with signs in brackets if needed. Complete each operation on a new line. State the final answer clearly and check by reversing one step.

Review quiz

1 / 4

Warm-up on absolute value: what is 4+3?

Practice questions

Practice 1 on absolute value: compute with the value 11.
Practice 2 on absolute value: change the numbers and repeat the same method.
Practice 3 on absolute value: write one sentence explaining the key rule.
Practice 4 on absolute value: invent a similar exam-style question and solve it.

Study notes

What is the main idea of absolute value?

Apply the stated formula or rule with clear steps, then check by reversing or substituting.

How should I revise this topic?

Cover the worked example, redo the practice without notes, then complete the MCQ set and log any wrong options.