Multiplying, dividing and order of operations · Grade 4
In Multiplying, dividing and order of operations (Grade 4) you practise 8 skills: Multiplying · Thinking about products · Dividing · Thinking about quotients · Zero and one · Divisibility by 3, 6 and 9 · Order of operations · Word problems. To multiply a two digit number, split it into tens and units and multiply each part: 23 × 4 = 20 × 4 + 3 × 4 = 80 + 12 = 92.
You can work out a product from one close to it: 49 × 8 is 50 × 8 take away 8, which is 400 − 8 = 392. You can split when you divide too: split the number being divided into parts that each divide exactly. So 1,536 ÷ 3 = (1,500 + 30 + 6) ÷ 3 = 500 + 10 + 2 = 512. You cannot divide by 0: no number times 0 gives a number that is not 0.
Tip: Before you work it out, estimate: which products or quotients of whole tens is the answer between? That makes a mistake easy to spot.
What you learn
Multiplying
For example: Work out: 25 × 3
Answer and solution
The answer: 75
Split the first number by place value and multiply each part: 25 × 3 = 20 × 3 + 5 × 3 20 × 3 = 60 5 × 3 = 15 60 + 15 = 75
Thinking about products
For example: Work out: 30 × 9
Answer and solution
The answer: 270
3 tens times 9 is 27 tens: 30 × 9 = 270
Dividing
For example: Work out: 27 ÷ 9
Answer and solution
The answer: 3
Take multiples of 9 away from 27, largest first: 9 × 3 = 27 27 − 27 = 0 The quotient is 3, with no remainder. Check: 3 × 9 = 27
Thinking about quotients
For example: Work out: 15,000 ÷ 3
Answer and solution
The answer: 5000
15 thousands divided by 3 is 5 thousands: 15,000 ÷ 3 = 5,000
Zero and one
For example: Choose the result: 15 × 0
- 1
- undefined
- 0
- 15
Answer and solution
The answer: 0
Any number times 0 is 0. 15 × 0 = 0
Divisibility by 3, 6 and 9
For example: Is 22 divisible by 3?
- No
- Yes
Answer and solution
The answer: No
The sum of the digits: 2 + 2 = 4 4 is not divisible by 3. So 22 is not divisible by 3. The answer: no.
Order of operations
For example: Work out: 20 ÷ 5 + 54
Answer and solution
The answer: 58
Each line does one operation: 20 ÷ 5 + 54 = 4 + 54 4 + 54 = 58
Word problems
For example: The school hall has 63 rows of chairs, with 8 chairs in each row. How many chairs are there in the hall?
Answer and solution
The answer: 504
63 × 8 = 504
The exercises are made by rules and the answers are worked out in code, so there are new exercises every time. The topic follows the new Israeli elementary programme (2023).