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MathidiaMathematics Academy
Integers and negative numbers
Lesson 8 of 75
Standard practice

Add directed numbers

Objective. Add integers using movement on a number line.

  1. 1. Learn
  2. 2. Worked example
  3. 3. Practice
  4. 4. Feedback
  5. 5. Continue

Learn: the key idea

Add directed numbers is built on a small number of dependable facts. Model directed number and calculate across zero. Represent the information first, choose a method deliberately, show each step and use an inverse operation or estimate to check that the result fits the question.

Worked example

Work out 4 − 11.

-9-6-4-1146−11
Number line from -9 to 6 with a jump of 11 backwards from 4
  1. 1Identify the mathematical information and what must be found.
  2. 2Represent it with a number line, diagram, table or expression where helpful.
  3. 3Apply the relevant fact carefully and keep each line clear.
  4. 4Check the result against the conditions in the question: -7.

Answer: -7

Concept mastery

Based on your past attempts at this lesson — the question types to practise again come first.

Complete a practice set to see your concept breakdown here.

Practice

Practice happens on its own screen, one question at a time. Answers stay hidden until you submit yours, and you can stop and pick up at the same question later.

Start practising

Common mistake. A common mistake in add directed numbers is to apply a remembered procedure before reading the signs, units or order carefully. Write the structure first, then calculate and check.

Your progress

Tick each step as you finish it. Your exact reading position is saved automatically, so Continue drops you back on the same line.

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