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Basic 1 · Mathematics · Number Operations

Taking Away (Subtraction)

In this topic you will learn that subtracting means taking away. You will use the minus sign (–).

By the end of these notes you should be able to:

  • Explain what subtracting means
  • Take away objects from a group
  • Write a subtraction sentence with – and =

What you already know

  • Adding numbers

Copy everything that has a blue line on its left into your notebook. The other parts are for reading.

Strand
Number
Sub-strand
Number Operations
Indicator
B1.1.2.1.1 – Demonstrate understanding of addition and subtraction

Introduction

Kwame has 9 mangoes. He gives 4 to his sister. How many are left? To find out, we take away.

1. What is Subtracting?

Subtracting: Taking some away from a group to find how many are left.

We use the minus sign (–) to subtract.

Nine mangoes with four crossed out
Figure 1: Taking 4 away from 9 mangoes Draw 9 mangoes, cross out 4 and write 9 – 4 = 5.Illustration: Sirbus

2. Subtracting by Counting Back

Steps

  1. Start at the bigger number.
  2. Count back the smaller number.
  3. The last number you say is the answer.

Example

9 – 4 = ?

  1. Start at 9.
  2. Count back 4: 8, 7, 6, 5.

Answer: 9 – 4 = 5

Example

There are 12 birds on a tree. 3 fly away. How many are left?

  1. Start at 12.
  2. Count back 3: 11, 10, 9.

Answer: 9 birds are left.

Tip: Words like "left", "take away" and "fly away" tell you to subtract.

Common mistake: In subtraction, always start with the bigger number.

New words

subtract
To take away.
minus (–)
The sign that means take away.
left
What remains after taking away.
difference
The answer when you subtract.

Summary

  • Subtracting means taking away.
  • Start at the bigger number and count back.
  • We write subtraction like this: 9 – 4 = 5.

Class activity: Take Away Game

  1. Put 10 bottle tops on the desk.
  2. Your partner takes some away and hides them.
  3. Count what is left.
  4. Say how many were taken away.

You need: Bottle tops, Bundles of sticks, Exercise books

Exercises

Answer in your exercise book first, then check your answers.

  1. 1. 6 – 2 = ?

    • A. 3
    • B. 4
    • C. 5
    • D. 8
    Show answer
    Answer: 4Count back 2 from 6: 5, 4.

  2. 2. Which sign means take away?

    • A. +
    • B. =
    • C. –
    • D. ×
    Show answer
    Answer: –The minus sign means take away.

  3. 3. 10 – 1 = 9

    • A. True
    • B. False
    Show answer
    Answer: TrueOne less than 10 is 9.

  4. 4. 8 – 3 = 6

    • A. True
    • B. False
    Show answer
    Answer: False8 – 3 = 5. Count back: 7, 6, 5.

  5. 5. 7 – 7 = ______

    Show answer
    Answer: 0If you take all 7 away, nothing is left.

  6. 6. Abena had 11 sweets. She ate 3. How many are left?

    Show answer
    Answer: 8 sweets11 – 3 = 8.

Homework

  1. Put 10 small stones in a bowl. Take some out. Write the subtraction sentence.