Primary Math: Fixing Number Sense Mistakes Before Exams

Quick answer

Ever felt your heart sink when you see a number sense question in an exam? You're not alone. It's common to lose marks on these questions because of small slips. Let's tackle these tricky spots together so you can confidently handle them before your next test.

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What you need to know

Number sense is about understanding how numbers work together. It's like seeing numbers as friends who help you solve problems. Operations are the actions you do with numbers, like adding or multiplying. Once you get how they relate, math becomes much easier.

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Common number sense mistakes

Misplacing the decimal

Decimal points can be sneaky. One small move can change $2.5$ to $25$, which is a big difference!

Step 1: Always line up decimals directly under each other when adding or subtracting.
Why: This keeps everything in the right place, so you don't mix up tens, ones, and tenths.

Quick check

1. Add 3.4 + 2.56 (line up the decimals).
2. Subtract 7.8 - 3.25 (line up the decimals again).

Answers: 5.96, 4.55

Forgetting order of operations

Remember BODMAS: Brackets, Orders (powers), Division/Multiplication, Addition/Subtraction. It's the order you solve parts of a math problem.

Step 1: Look for brackets first and solve what's inside.
Why: Brackets group numbers and operations that must be handled first.

Step 2: Handle any powers (like squaring a number).
Why: Powers come next in the order to maintain the correct sequence.

Quick check

1. Calculate $2 + (3 \times 4)$.
2. Solve $5^2 - 3$.

Answers: 14, 22

Revision checklist

• Decimals: Double-check their placement, especially in subtraction.
• Order of Operations: Always follow BODMAS to avoid wrong answers.
• Estimation: Use it to quickly check if your answer makes sense.

Exam tip

Presentation is key. Write neatly and clearly, especially with decimals and fractions. This helps you avoid mistakes and makes it easier for the examiner to follow your work.

Worked examples

Question

Calculate $3.5 \times 2.4$.

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Solution

Step 1: Ignore the decimals and multiply $35 \times 24$.
Why: It simplifies the multiplication. You can add the decimals back later.

Step 2: Multiply $35 \times 24$ to get $840$.
Why: This is the product without the decimals.

Step 3: Count the decimal places in the original numbers (1 in each), so move the decimal in $840$ two places left to get $8.40$.
Why: This corrects the placement of the decimal in the final answer.

Quick summary

• Line up decimals carefully in calculations.
• Always follow BODMAS for order of operations.
• Double-check your work with estimation.
• Write neatly for better clarity and fewer mistakes.
• Practice, practice, practice — short sessions every day help more than cramming.

FAQ

What if I forget BODMAS during an exam?
Try to remember it as a story: Brackets are like a small house, Orders like the sun shining on it, Division and Multiplication like cutting and serving food, and Addition/Subtraction like eating and enjoying.

Why do decimals confuse me so much?
Decimals are tricky because they represent small parts. Practice lining them up and use estimation to see if your answer makes sense.

Is it okay to estimate in exams?
Yes, especially when checking your work. Estimation helps you know if an answer is reasonable.

How can I improve my number sense quickly?
Short, daily practice sessions are best. Try explaining problems to someone else; teaching helps you learn.

Related Topics You Should Learn Next

• Primary Math Number Sense
• Primary Math Operations Guide

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