Balance subtraction equations – up to 18
key notes :
What is a Balanced Equation? ⚖️
A balanced subtraction equation is when both sides of the equation are equal.
Example: 12 - 5 = 7 ✅ Both sides equal 7, so it is balanced.
Subtraction Means “Take Away” ➖
Subtraction is taking away some objects from a group.
Example: 10 – 3 = 7 (Take away 3 from 10, 7 left)
Checking Balance with “What Number Makes It True?” 🔍
Sometimes the equation has a missing number. Find it!
Example: 14 – ? = 9
Use Counters or Drawings 🎨
Draw dots, stars, or use fingers to see subtraction visually.
Example: 8 – ? = 5
- Draw 8 stars, cross out some until 5 remain.
- 3 stars crossed → 8 – 3 = 5 ✅
Equations Can Have Missing Numbers Anywhere ❓
Missing number can be on left, right, or in the middle.
Examples:
- ? – 4 = 7 → ? = 11
- 12 – ? = 6 → ? = 6
- 15 – 8 = ? → ? = 7
Always Keep the Equation Balanced ⚖️
Whatever you do on one side, the other side must be equal.
Tip: Count carefully to make sure both sides match.
Practice Makes Perfect! ✏️
Start with numbers up to 10, then go up to 18.
Use real-life examples:
“I have 18 candies. I ate 7. How many are left?” → 18 – 7 = 11 ✅
Fun Tip:
- Think of subtraction as “making both sides the same” like a balance scale ⚖️.
- If both sides weigh the same (numbers equal), the equation is balanced.
Learn with an example
Which number makes the equation true?
6 − 4 = 3 − ?
First, subtract 6 − 4:
6 – 4 =3 – ?
2 = 3 – ?
Now decide which number makes the subtraction number sentence true. You can think of a subtraction fact you know, or you can subtract to find the answer.
The subtraction fact is:
3 − 1 = 2
Did you remember this subtraction fact? If not, you can find the answer by subtracting.
Subtract:
3 − 2 = 1
The missing number is 1.
Which number makes the equation true?
___− 4 = 3 − 1
First, subtract 3 − 1:
? – 4 = 3 – 1
? – 4 = 2
Now decide which number makes the subtraction number sentence true. You can think of a subtraction fact you know, or you can add to find the answer.
The subtraction fact is:
6 − 4 = 2
Did you remember this subtraction fact? If not, you can find the answer by adding.
Add:
2 + 4 = 6
The missing number is 6.
Which number makes the equation true?
3 − 3 = ___ − 4
First, subtract 3 − 3:
3 − 3 = ? − 4
0 = ? − 4
Now decide which number makes the subtraction number sentence true. You can think of a subtraction fact you know, or you can add to find the answer.
The subtraction fact is:
4 − 4 = 0
Did you remember this subtraction fact? If not, you can find the answer by adding.
Add:
0 + 4 = 4
The missing number is 4.
Let’s practice!🖊️
