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Lesson 4 of 6
Lesson 4 of 6
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Numbers in binary
I can convert between decimal numbers and binary.
Lesson details
Key learning points
- Natural numbers (like 1, 2, 3...) can be represented in binary, which uses only 0s and 1s.
- Each binary digit (bit) represents a power of 2, decimal digits represent powers of 10.
- You can convert a decimal number to binary by finding which powers of 2 add up to that number.
- You can convert binary back to decimal by adding the values of all the 1s in the binary number.
Keywords
Decimal - a base-10 number system that uses the digits 0 to 9
Binary - a number system that uses the digits 0 and 1 to represent data
Common misconception
Binary uses the same place value system as decimal.
Binary is a base-2 number system, whereas decimal is a base-10 number system.
Some pupils may find it easier to peform conversions on paper using the tables modelled in the slide deck, these are provided on the worksheet linked to the lesson if needed.
Teacher tip
Equipment
Licence
This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Prior knowledge starter quiz
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6 Questions
Q1.What is the smallest unit of data in a computer?
What is the smallest unit of data in a computer?
Q2.Put these steps in order to measure the size of binary data:
Put these steps in order to measure the size of binary data:
Q3.Why do computers use binary to represent information?
Why do computers use binary to represent information?
it is easier for humans to read
it makes computers faster
it allows for more colours
Q4.If you have 4 bits, how many different values can you represent?
If you have 4 bits, how many different values can you represent?
Q5.Match each keyword to its definition:
Match each keyword to its definition:
a system using only 0 and 1
the smallest unit of data (0 or 1)
a series of items in a set order
to show or stand for something
Q6.What does having more bits allow you to do?
What does having more bits allow you to do?
use more colours in your project
make your computer lighter
draw better pictures
Assessment exit quiz
Download quiz pdf
6 Questions
Q1.What number system does binary use?
What number system does binary use?
base-10
base-8
base-16
Q2.A binary digit is also called a ?
A binary digit is also called a ?
Q3.Match the binary value to its decimal value.
Match the binary value to its decimal value.
10
15
9
2
Q4.What is the decimal value of the binary number 1101?
What is the decimal value of the binary number 1101?
11
12
14
Q5.Match the decimal value to its binary value.
Match the decimal value to its binary value.
101
111
011
Q6.Which of these binary numbers is equal to the decimal number 21?
Which of these binary numbers is equal to the decimal number 21?
11001
10011
11100