Mental Maths Strategies That Actually Work for Primary Students

Mental maths skills don’t come from drilling facts faster. They come from teaching children flexible strategies to manipulate numbers efficiently. Here are the most effective mental computation strategies for primary students.

Why Mental Maths Matters

Students with strong mental computation skills:

Calculate more efficiently
Develop number sense and flexibility
Check if answers are reasonable
Build mathematical confidence
Perform better in problem-solving

Mental maths isn’t about speed—it’s about smart thinking.

Addition Strategies

1. Making Ten

Use 10 as a benchmark number.

Example: 8 + 7

Think: “8 needs 2 to make 10”
Split 7 into 2 and 5
8 + 2 = 10, then 10 + 5 = 15

When to use: Single-digit addition, especially crossing 10

2. Compensation (Rounding and Adjusting)

Round to friendly numbers, then adjust.

Example: 48 + 35

Round 48 to 50 (added 2)
Add: 50 + 35 = 85
Subtract the 2 back: 85 - 2 = 83

When to use: Numbers close to multiples of 10 or 100

3. Breaking Apart (Partitioning)

Split numbers by place value.

Example: 37 + 45

Split: 30 + 7 and 40 + 5
Add tens: 30 + 40 = 70
Add ones: 7 + 5 = 12
Combine: 70 + 12 = 82

When to use: Two-digit addition, understanding place value

4. Doubles and Near-Doubles

Use known doubles as anchors.

Example: 7 + 8

Know: 7 + 7 = 14
Think: 8 is one more than 7
So 7 + 8 = 14 + 1 = 15

When to use: Numbers that are the same or differ by 1 or 2

Subtraction Strategies

1. Counting Up

Count from smaller to larger number.

Example: 83 - 67

Start at 67, count to 83
67 + 3 = 70
70 + 10 = 80
80 + 3 = 83
Total: 3 + 10 + 3 = 16

When to use: Numbers close together, making change

2. Compensation

Adjust to friendly numbers.

Example: 75 - 29

Round 29 to 30 (added 1)
75 - 30 = 45
Add back 1: 45 + 1 = 46

When to use: Subtracting numbers ending in 8, 9

3. Place Value Splitting

Subtract in parts.

Example: 85 - 32

Subtract tens: 85 - 30 = 55
Subtract ones: 55 - 2 = 53

When to use: When compensation isn’t obvious

Multiplication Strategies

1. Doubling and Halving

Use easy multiplies to find harder ones.

Example: 8 × 15

Know 4 × 15 = 60
Double it: 60 × 2 = 120

Or: 16 × 5

Half of 16 = 8
Double of 5 = 10
8 × 10 = 80 (same answer!)

When to use: When one number is even and one is 5 or 50

2. Breaking Apart (Distributive Property)

Split numbers into friendlier parts.

Example: 7 × 12

Think: 7 × 10 = 70
And: 7 × 2 = 14
Add: 70 + 14 = 84

When to use: Multiplying by 11, 12, teen numbers

3. Using Known Facts

Build from facts you know.

Example: 7 × 8 (if unknown)

Know 7 × 7 = 49
Add one more 7: 49 + 7 = 56

When to use: Extending known multiplication facts

4. Multiplying by 5

Think of 5 as half of 10.

Example: 24 × 5

Calculate 24 × 10 = 240
Half it: 240 ÷ 2 = 120

When to use: Any number times 5

Division Strategies

1. Think Multiplication

Division is the inverse of multiplication.

Example: 56 ÷ 7

Think: “7 times what equals 56?”
7 × 8 = 56
So 56 ÷ 7 = 8

When to use: Always! Strong multiplication helps division

2. Halving

For dividing by 2, 4, 8…

Example: 96 ÷ 4

Half of 96 = 48
Half of 48 = 24

When to use: Dividing by powers of 2

3. Chunking

Take away groups you know.

Example: 85 ÷ 5

Take away 5 × 10 = 50, leaving 35
Take away 5 × 7 = 35
Total: 10 + 7 = 17

When to use: Larger division problems

Teaching Mental Maths Effectively

1. Start Orally No written work initially. Focus on thinking and explaining.

2. Share Strategies Multiple students solve the same problem different ways. All valid strategies are valuable.

3. Visualize Use number lines, hundred charts to show thinking.

4. Practice Regularly Short daily practice (5-10 minutes) beats occasional long sessions.

5. Celebrate Cleverness Praise smart strategies, not just speed or accuracy.

6. Make It Fun Games, challenges, real-world contexts make practice engaging.

Mental Maths Games

Target Number:

Give target (e.g., 50)
Roll dice, use operations to reach target
Multiple solutions possible

Around the World:

One student stands, faces neighbor
Teacher asks question
First to answer correctly moves on
Emphasize strategy over speed

Estimation 180:

Show image briefly
Students estimate quantity
Discuss strategies

Number Talks:

Daily 10-minute discussions
One problem, multiple strategies
Students explain thinking

Common Mistakes to Avoid

Don’t:

Focus only on speed drills
Demand one “correct” method
Move to algorithms before strategies
Test under pressure
Compare students publicly

Do:

Value multiple strategies
Give thinking time
Celebrate clever approaches
Build from concrete to mental
Practice in low-stakes ways

Progression by Year Level

Years 1-2: Making 10, doubles, simple place value splits

Years 3-4: Rounding/compensation, distributive property, known facts extension

Years 5-6: Complex compensation, combining strategies, decimal/fraction strategies

Assessing Mental Maths

Look for:

Multiple strategy use
Efficient strategy selection
Ability to explain thinking
Flexibility when one strategy doesn’t work

Not just:

Speed
Single correct method
Memorization without understanding

The Bottom Line

Mental maths is about smart thinking, not fast thinking. When children have a toolkit of strategies and the flexibility to choose appropriately, they become confident, capable mathematicians. Teach strategies explicitly, practice regularly in low-pressure contexts, and celebrate mathematical thinking. That’s how you build genuine mental computation skill.