Primary 4 · Number & Algebra
P4 four operations of whole numbers
In P4, your child multiplies and divides bigger whole numbers in columns, and rounds them to the nearest 10, 100 or 1000 to estimate an answer. Most lost marks come from rounding by the wrong digit, or cutting a number off instead of rounding it.
- Taught in
- Term 1
- Syllabus
- 3 skills
- Usual slip
- Cuts the number off
What your child learns in P4 four operations of whole numbers
Three skills, each with what it looks like on a worksheet.
See the syllabus wording
- rounding numbers to the nearest 10, 100 or 1000
- use of ≈
- multiplication algorithm: up to 4 digits by 1 digit, up to 3 digits by 2 digits
- division algorithm (up to 4 digits by 1 digit)
Round and estimate
To round to the nearest hundred, look at the tens digit, right of the hundreds. 5 or more rounds up. The sign ≈ means "is about", so 3482 ≈ 3500. Rounding first gives a quick estimate to check an answer.
| Point | Value |
|---|---|
| 3482 | 3482 |
Multiply in columns
Up to 4 digits by 1 digit, and up to 3 digits by 2 digits. With a 2-digit number your child writes two rows, one for the ones and one for the tens with a placeholder 0, then adds them.
Long division
Up to 4 digits by 1 digit. Work from the left: divide, multiply, subtract, bring down, one place at a time. What is left over is the remainder, written with R, so 3754 ÷ 7 = 536 R 2.
Key facts and formulas
- RoundingLook at the digit to the right of the place. 5 or more, round up.nearest 10 → nearest 100 → nearest 1000 →
Point Value 36 482 36482 - Multiply in columnsMultiply by the ones, then by the tens, then add the two rows.
- Long divisionFrom the left: divide, multiply, subtract, bring down.
Words to know
- Round
- Change a number to the nearest 10, 100 or 1000.
- Nearest hundred
- The hundred a number is closest to. 3482 is nearer 3500 than 3400.
- 5 or more
- When the digit to the right is 5 or more, round up. Below 5, round down.
- Estimate
- A quick, rounded answer that tells you roughly what to expect.
- ≈
- Is about, or is approximately equal to.
The sentence that costs the mark
Round 4567 to the nearest hundred.
What the working usually does
cuts off4567=4500
Keeps the hundreds and drops the 67, which feels like rounding down. But cutting the rest off is not rounding.
What the question asked
rounds4567=4600
Reads the tens digit, 6, to decide. 6 is 5 or more, so the hundreds go up from 4500 to 4600.
4500 is a real "nearest hundred" number, and cutting off feels like rounding down, so nothing looks careless. The check is the deciding digit: the tens digit is 6, past halfway, so 4567 rounds up.
The same P4 four operations of whole numbers question, worked properly
Lah works through it the way she does every question in StudyLah: one step at a time, marking the picture as she goes.
47 380 is rounded to the nearest hundred. What number do you get?
- To round to the nearest hundred, look at the digit just to the right of the hundreds. In 47 380, that is the tens digit, 8.
- 8 is 5 or more, so round up: 47 380 ≈ 47 400. Cutting off the 80 gives 47 300, which is the wrong hundred.
- Halfway between 47 300 and 47 400 is 47 350. 47 380 is past halfway, so it is nearer 47 400.
- So 47 380 rounded to the nearest hundred is 47 400.
Every question in StudyLah comes with a walkthrough like this one.
Try it freeThree quick P4 four operations of whole numbers questions
Try them together, then tap to check.
Question 1
Calculate 476 × 28.
Show answer
Answer13 328. 476 × 8 = 3808 and 476 × 20 = 9520. Add the two rows, 3808 + 9520 = 13 328.
Question 2
A farm has 2545 eggs. Each tray holds 6 eggs. What is the least number of trays needed to hold all the eggs?
Show answer
Answer425. 2545 ÷ 6 = 424 R 1, and the 1 egg left over still needs a tray.
Question 3
Rounding a number to the nearest ten gives 5480. Find the greatest number it could have been.
Show answer
Answer5484. Numbers from 5475 to 5484 round to 5480. 5485 rounds up to 5490.
Helping at home
How to tell it has clicked
Ask "which digit tells you whether to round up or down?" If they point to the digit to the right of the rounding place, they have it. If they point at the place itself, that is the slip.
A sense-check also works: is the number past halfway? Past halfway rounds up. A child who checks the halfway mark rarely cuts a number off by mistake.
Try this tonight
At the supermarket, round each price to the nearest dollar before adding a rough total. $4.60 becomes $5, not $4. Ask "is it nearer 4 or 5?"
Estimate first, then let them work it out exactly and compare the two. If they are far apart, one of them is wrong, and catching that is the reason to estimate.
Before and after P4 four operations of whole numbers
Builds on
Primary 3 Multiplication and DivisionMultiplies and divides, and reads the remainder
You are here
Primary 4 Four Operations of Whole Numbers
Multiplies, divides and rounds bigger numbers
Head Start
The P4 to P5 Maths jump: what to revise before P5One of three P4 topics to revise before P5 Term 1
Leads to
Primary 5 Whole Numbers and Four OperationsDoes the operations in the right order
The methods your child will use here
More in Primary 4
Struggling with the working rather than the topic itself? How to help your child with problem sums
See how your child is doing on this topic
StudyLah marks each step separately, so you can see whether it was the setup or the arithmetic that cost the mark.