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\( \definecolor{colordef}{RGB}{249,49,84} \definecolor{colorprop}{RGB}{18,102,241} \)
International Baccalaureate · PYP 0

Subtracting Within 10

⌚ ~146 min ▢ 16 blocks ✓ 114 exercises ➣ Prerequisites : Order and Position, Adding Within 10, Comparing Quantities
I What is Subtraction?

You have 8 cubes and you give 5 cubes to your friend.
Figure \(\quad\) take away \(\quad\) Figure
How many cubes do you have left?

We cross out the 5 cubes given away: they are taken away.
Figure
We count the cubes that are not crossed out: one, two, three. There are 3 cubes left. Taking away from a group to find how many are left is called subtraction.


Definition — Subtraction
Subtraction means taking away from a group to find out how many are left. The answer in subtraction is called the difference. In mathematics, we use special symbols for subtraction:
  • The minus sign (\(-\)) means to subtract or take away.
  • The equals sign (\(=\)) shows that what is on one side is the same amount as what is on the other side.
Here are different ways to show “eight minus five equals three”:
  • With numbers: $$\textcolor{colordef}{8} - \textcolor{colorprop}{5} = \textcolor{olive}{3}$$
  • Cubes:
    Figure \(-\) Figure \(=\) Figure
  • Fingers:
    Figure \(-\) Figure \(=\) Figure
  • Words: $$\textcolor{colordef}{\text{eight }}\text{minus}\textcolor{colorprop}{\text{ five}}\text{ equals }\textcolor{olive}{\text{three}}$$
Skills to practice
  • Subtracting Fruits Within 5
  • Subtracting Cubes Within 5
  • Subtracting Fingers Within 5
  • Subtracting in the Ten-Frame Within 5
  • Subtracting Fruits Within 10
  • Subtracting Cubes Within 10
  • Subtracting Fingers Within 10
  • Subtracting in the Ten-Frame Within 10
II How to Subtract
Method — Subtracting by Taking Away
A simple way to subtract is by “taking away.” You start with the total number and then put down the number of fingers you are subtracting.
Solve: \(5 - 2 = ?\)
  • Step 1: Show the starting number. Hold up 5 fingers. This is your total.
    Figure
  • Step 2: Take away by putting fingers down. You need to subtract 2, so put down 2 fingers, one at a time.
    Figure \(\rightarrow\) Figure \(\rightarrow\) Figure
  • Step 3: Count what is left. Count the fingers that are still up. There are 3 fingers left.
The answer is 3.
\(5 - 2 = 3\)
Figure \(-\) Figure \(=\) Figure
Skills to practice
  • Subtracting Numbers Within 5
  • Subtracting Numbers Within 10
III Subtracting on the Number Line
Method — Using a Number Line to Subtract
We can also use a number line to subtract: subtracting means taking steps backward on the line.
Solve: \(7 - 3\)
  1. Start at the first number. Find the number 7 on the number line. This is your starting point.
  2. Jump backward. The second number, 3, tells you how many jumps to make. Since we are subtracting, we move to the left, where the numbers get smaller. Make 3 jumps backward.
  3. Find your landing spot. The number you land on is the answer.
Figure
After 3 jumps backward, you land on 4. So, \(7 - 3 = 4\).
Skills to practice
  • Subtracting on the Number Line
IV Solving Subtraction Problems

There are 6 apples in the basket. Hugo eats 2 of them (they are crossed out).
Figure
How many apples are left? Nothing is written: we must find what to do.

For a problem, we look for what we know, we try with fingers or cubes, we check by counting again, and we say the answer. Eating is taking away: we subtract. We count the apples that are not crossed out: one, two, three, four.
Figure
\(6-2=4\). Check: we count the apples that are not crossed out: four. Say: there are 4 apples left.


Example
Aisha has 5 red apples. Hugo has 3 blue apples. How many more apples does Aisha have than Hugo?
Figure

Careful: we hear more, but to find the difference we subtract. We match the apples one to one. Two red apples have no partner: they are the extra ones.
Figure
\(5-3=2\). Aisha has 2 more apples than Hugo. Check: 3 matched apples and 2 extra ones make 5 again.

Skills to practice
  • Finding What Is Left
  • Finding the Difference
  • Moving Back on the Track
V Going further
Skills to practice
  • Completing Subtraction Equations with Pictures up to 5
  • Completing Subtraction Equations with Pictures up to 10
  • Quiz