ENFR

🇨🇩 Operations

Subtracting with objects and numbers

⏱ 15 minOfficial programme: CD-P1-OPE-02

Your answers are checked, but your progress is not saved. To save it, sign in with your family code, or ask a parent to open this course from the dashboard.

🎯 In this lesson, you will learn to

  • Do simple additions and subtractions from manipulation.

The lesson

Introduction

Mama Neema has 5 mangoes: 🥭🥭🥭🥭🥭. She sells 2. How many mangoes are left? To find out, we subtract. To subtract is to take away.

Explanation

We write a subtraction with the sign −.

5 − 2 = 3

We read: “five minus two equals three”.

🥭🥭🥭🥭🥭: we take away 2.

🥭🥭🥭 are left, so 3.

Explanation

There are several ways to subtract.

  • Cross out the objects taken away, then count what is left.
  • Count backwards: for 7 − 2, say “6, 5”. The result is 5.
  • Use your fingers: raise 7 fingers, fold down 2 fingers.

Special cases: 4 − 0 = 4 and 4 − 4 = 0.

Explanation

Addition helps you subtract.

3 + 2 = 5, so 5 − 2 = 3.

For a bigger number, go through 10.

14 − 4 = 10.

If we take away 6 from 14: 14 − 4 = 10, then 10 − 2 = 8.

Worked example

Kalala has 7 bananas: 🍌🍌🍌🍌🍌🍌🍌. He eats 3. How many are left?

Step 1: I start from 7.

Step 2: I take away 3 bananas. I count backwards: 6, 5, 4.

Answer: 7 − 3 = 4. There are 4 bananas left.

Worked example

Mbuyi has 12 hens. He sells 5. How many are left?

Step 1: I write 12 − 5.

Step 2: I take away 2 to reach 10: 12 − 2 = 10.

Step 3: I still have to take away 3: 10 − 3 = 7.

Answer: 12 − 5 = 7. There are 7 hens left.

Worked example

Malaika has 3 stones: 🪨🪨🪨. She gives them all to Bolingo. How many does she have left?

Step 1: I start from 3.

Step 2: I take away 3.

Answer: 3 − 3 = 0. She has none left.

Watch out

Watch out: we always start from the bigger number. 5 − 2 is not 2 − 5. When you count backwards, do not count the starting number. For 5 − 2, say “4, 3”. Do not say “5, 4”.

Key points

  • To subtract is to take away.
  • The sign for subtraction is −.
  • We start from the bigger number.
  • We can cross out, count backwards or go through 10.
  • 4 − 0 = 4 and 4 − 4 = 0.
  • Addition helps: 3 + 2 = 5, so 5 − 2 = 3.

✍️ Exercises

Answer one exercise at a time. Your answer is checked right away, with an explanation.

Exercise 1 of 8

★ Easy

There are 6 oranges: 🍊🍊🍊🍊🍊🍊. We eat 2. How many are left?

Your answer