Primary 5 · Number & Algebra
P5 whole numbers and four operations
In P5, your child works with numbers up to 10 million, multiplies and divides by 10, 100, 1000 and their multiples, and uses brackets in expressions. All of it is done without a calculator. Most lost marks come from the order: × and ÷ come before + and −.
- Taught in
- Term 1
- Syllabus
- 3 skills
- Usual slip
- Adds first
What your child learns in P5 whole numbers and four operations
Three skills, each with what it looks like on a worksheet.
See the syllabus wording
- reading and writing numbers in numerals and in words
- multiplying and dividing by 10, 100, 1000 and their multiples without calculator
- order of operations without calculator
- use of brackets without calculator
Numbers up to 10 million
Your child reads and writes numbers up to 10 million, in numerals and in words. A 0 holds each empty place, and the numeral is grouped in threes from the right.
| Numeral | In words |
|---|---|
| 2 050 300 | two million, fifty thousand and three hundred |
| 7 400 016 | seven million, four hundred thousand and sixteen |
By 10, 100, 1000 and their multiples
Without a calculator, your child multiplies and divides by 10, 100, 1000 and multiples such as 300. For 46 × 300, they do 46 × 3 = 138, and 138 hundreds is 13 800.
Order of operations and brackets
Brackets first. Then × and ÷ from left to right, then + and − from left to right. × and ÷ have equal priority, so neither always comes first: 12 ÷ 2 × 3 = 18.
| Expression | Do first | Value |
|---|---|---|
| 20 − 4 × 3 | 4 × 3 | 8 |
| (20 − 4) × 3 | 20 − 4 | 48 |
| 12 ÷ 2 × 3 | 12 ÷ 2 | 18 |
Key facts and formulas
- Numbers to 10 million2 030 005: two million, thirty thousand and five
Millions Hundred thousands Ten thousands Thousands Hundreds Tens Ones 2 0 3 0 0 0 5 - Order of operationsBrackets first. Then × and ÷ from left to right, then + and −.Example
- × or ÷ by multiples of 10Split off the zeros: use the digit, then the 10, 100 or 1000.Example
Words to know
- Brackets
- The part of an expression worked out first, as in (20 − 4) × 3.
- Order of operations
- Brackets first, then × and ÷, then + and −.
- Left to right
- How to work through operations of equal priority, such as × and ÷.
- Equal priority
- × and ÷ rank the same, and so do + and −. Neither always comes first.
The sentence that costs the mark
Find the value of 5 + 3 × 10.
What the working usually does
add first5 + 3 × 10=80
Adds the 5 and 3 because they come first, then times 10. The arithmetic is fine, the order is not.
What the question asked
times first5 + 3 × 10=35
Does 3 × 10 first, because × and ÷ come before + and −, then adds the 5.
Both are two clean operations on the same three numbers, and 80 is a believable answer. Nothing in the arithmetic is wrong. Only the order is.
The same P5 whole numbers and four operations 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.
Find the value of 7 + 4 × 8 − 5.
- In 7 + 4 × 8 − 5, the order of operations says multiplication comes before addition and subtraction, wherever it sits.
- So do 4 × 8 = 32 first. Adding 7 and 4 first, to get 11, is the slip.
- Only + and − are left, so work from left to right: 7 + 32 = 39, then 39 − 5 = 34.
- So the value is 34.
Every question in StudyLah comes with a walkthrough like this one.
Try it freeThree quick P5 whole numbers and four operations questions
Try them together, then tap to check.
Question 1
Evaluate 100 − 6 × (7 + 5).
Show answer
Answer28. Brackets first, 7 + 5 = 12. Then 6 × 12 = 72, and 100 − 72 = 28.
Question 2
What is 408 × 700?
Show answer
Answer285 600. 700 is 7 hundreds, so 408 × 7 = 2856, and 2856 hundreds is 285 600.
Question 3
Express four million, twenty thousand and eighty as a numeral.
Show answer
Answer4 020 080. That is 4 000 000 + 20 000 + 80, with a 0 in each empty place.
Helping at home
How to tell it has clicked
You do not need to do the sum to check this. Read 5 + 3 × 10 aloud and ask your child what they do first. The answer is the 3 × 10, every time.
A child who reaches for the multiplication first, wherever it sits in the line, has it. A child who starts at the left and works across has the habit that turns 35 into 80.
Try this tonight
Read the sum aloud with the multiplication as one chunk: "five, plus three tens." Said that way, nobody adds the five in first.
Try it on any mixed sum in the homework. Say the × or ÷ part as one amount first, then the rest.
Before and after P5 whole numbers and four operations
Builds on
Primary 4 Four Operations of Whole NumbersMultiplies, divides and rounds bigger numbers
Builds on
Primary 4 Numbers to 100 000Reads each digit by its place value
You are here
Primary 5 Whole Numbers and Four Operations
Does the operations in the right order
Leads to
Primary 6 AlgebraUses a letter for an unknown number
Leads to
Primary 6 AverageTurns an average into a total
The methods your child will use here
In the PSLE's hardest questions
More in Primary 5
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.