Multiply by 10
43 x 10 = 430 because each digit becomes ten times the value.
The digits move one place to the left in value.
Year 5
Multiply and divide numbers mentally, drawing upon known facts
Use known facts and place value to multiply and divide mentally by 10, 100 and 1000.
Lesson overview
Number - multiplication and division
Multiplying by 10, 100 or 1000 changes the value of each digit. Dividing does the reverse. It is not about adding or removing zeroes blindly. It is about the place value moving.
Divide by 100
6,300 / 100 = 63 because each digit becomes one hundredth of the value.
Dividing by 100 moves the digits two places to the right in value.
Use known facts
If 6 x 7 = 42, then 60 x 7 = 420 and 420 / 7 = 60.
Known facts help with larger related facts.
Worked example
Calculate 54 x 100.
- Multiplying by 100 makes each digit one hundred times the value.
- 54 has 5 tens and 4 ones.
- Those become 5 thousands and 4 hundreds.
- So 54 x 100 = 5,400.
Round 1: Learn it
Use place value and known facts rather than relying on a shortcut rule.
Finish this round to unlock Round 2: Show you know it.
Question 1
What is 43 x 10?
Question 2
What is 6,300 / 100?
Question 3
If 6 x 7 = 42, what is 60 x 7?
Question 4
Calculate 54 x 100.
Question 5
What is 8,000 / 1000?
Common mistakes
Watch for these as you work through the lesson.
- Adding zeroes without thinking about place value.
- Moving the digits the wrong way when dividing.
- Forgetting to use a known multiplication fact first.
Related topics
These ideas connect closely to this lesson.
- Identify multiples and factors, including finding all factor pairs of a number, and common factors of two numbers.
- Multiply numbers up to 4 digits by a one- or two-digit number using a formal written method, including long multiplication for two-digit numbers.