IllumiTutor logoIllumiTutorBETA
A friendly flat-vector scene of large place-value blocks and number cards arranged in groups of three digits, beside a calculator, in IllumiTutor navy and amber on an off-white background.

Whole Numbers

Reading numbers up to 10 million, the four operations, order of operations with brackets, and estimating answers to check your work.

⏱ 7 min · 🎯 4 things to master

Numbers in P5 suddenly get big — really big. You will see seven-digit numbers like the population of a country or the price of a HDB block of flats. The good news is that a big number follows the exact same rules as a small one. Once you can read it, group it, and keep your operations in the right order, a number with seven digits is no scarier than one with two. Let's build it up.

Parents: let your child predict before they reveal each step. The blue dotted words are tappable definitions, and the "Method tip" boxes name exactly what a PSLE marker rewards in the working — not just the final number.

By the end you'll be able to read numbers up to 10 million, do all four operations, follow the correct order of operations with brackets, and estimate to check your answer. Here we go.

Reading numbers to 10 million

A big number is easier to read when you split it into groups of three digits from the right. Each group has a . So 4 250 000 reads as "four million, two hundred and fifty thousand". The trick is to find the first, name its place, then read across.

Think of the population of a town: 1 080 600 is "one million, eighty thousand, six hundred". Notice the zero in the ten-thousands place — you still say it as a gap, you do not skip it.

🤔 Predict first: How do you read the number 3 060 000?

The four operations

You already know how to add, subtract, multiply and divide. With big numbers, the only change is to line up your digits carefully by place value. When you , keep each digit in its column so nothing drifts.

Imagine sharing 9 248 sweets equally among 8 classes. That is 9248 ÷ 8 = 1156 sweets per class. Check it: 1156 × 8 = 9248. The check is the part most students skip, but it catches mistakes fast.

🤔 Predict first: A factory packs 6 384 biscuits equally into 6 boxes. How many biscuits are in each box?

Order of operations and brackets

When a sum mixes operations, you cannot just work left to right. There is an order. Do anything inside first, then multiply and divide, then add and subtract. This is the .

Try 20 + 3 × 4. The times comes first: 3 × 4 = 12, then 20 + 12 = 32. If you went left to right you would wrongly get 92. Now try a bracket: (20 + 3) × 4 = 23 × 4 = 92. The bracket changes everything.

🤔 Predict first: What is the value of 6 + 2 × 5?

Estimating to check

A smart student never trusts a big answer blindly. Before or after working, you by rounding to get a rough size. If your real answer is far from your estimate, something went wrong.

Say you work out 4 980 × 19 and get 94 620. Round to 5000 × 20 = 100 000. Your answer 94 620 is close to 100 000, so it looks sensible. If you had got 9 462, the estimate would warn you that you slipped a place.

🤔 Predict first: To quickly check 612 × 48, which estimate is best?

Watch out — these are easily mixed up

Quick recap

🎯 Mastery check

Answer all 6 — your progress is saved on this device.

  1. How do you read the number 2 005 400?

  2. What is 7 + 4 × 6?

  3. What is the value of (8 + 7) × 3?

  4. A box holds 5 280 nails shared equally into 6 packs. How many nails per pack?

  5. Which is the best quick estimate for 397 × 21?

  6. In the sum 30 − 4 × 5, what should you do first, and what is the final answer?