Size Matters
The units that measure data: the bit and the byte, then kilobytes, megabytes, gigabytes and terabytes, and the AQA rule that each step up the ladder is 1000, not 1024.
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Free interactive practice on the steps that lose marks under exam pressure.
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How we measure data
Everything a computer stores is measured in the same family of units, from the tiny bit up to the huge terabyte. Get the units and the steps between them right and file-size questions become easy marks. This module works through the bit and the byte, the bigger units, and the one rule AQA insists on: each step up is a thousand, not 1024.
Data words to know
Learn these before you measure any file.
The right rule against the trap
The units are easy; the convention is where marks are won or lost.
Multiply or divide by a thousand
In the exam, remember two numbers: a byte is 8 bits, and every jump to the next unit is a thousand, not 1024. So to go from bytes to kilobytes divide by 1000, and from kilobytes to megabytes divide by 1000 again; multiply the other way. Keep the units in the right order from smallest to largest, and always use 1000, not 1024, or you lose easy marks.
Match the unit
- bit
- byte
- kilobyte
- megabyte
- a single 0 or 1
- a group of 8 bits
- one thousand bytes
- one thousand kilobytes
Match the example
- a bit
- a byte
- a megabyte
- a gigabyte
- the smallest piece of data
- enough to store one character of text
- about the size of a small photo
- about the size of a long film
How many bytes in a kilobyte?
In the AQA convention, how many bytes are there in one kilobyte?
- 1000
- 1024
- 100
- 8
True about data units
Select the TWO true statements about units of data.
- One byte is made of 8 bits
- AQA uses 1000, not 1024, for each step up
- A bit can hold any number from 0 to 9
- A gigabyte is smaller than a megabyte
Work out the file size
A photo is 3 megabytes in size. There are 1000 kilobytes in a megabyte. Multiply 3 by 1000 to find the size of the photo in kilobytes. What is the answer?
Order the units
Put these units of data in order, smallest first.
- bit
- byte
- kilobyte
- megabyte
Complete the rules
The smallest unit of data is a _____, a single 0 or 1. A group of 8 bits is a _____. In the AQA convention there are _____ bytes in a kilobyte. Each jump to the next unit multiplies by a _____.
Spot the correct facts
Tap the TWO correct facts about data units.
- a byte is made of 8 bits
- there are 1000 bytes in a kilobyte
- a bit can be any digit from 0 to 9
- a kilobyte is bigger than a megabyte
Apply the rule
Read each case and choose the best answer.
- You need to convert 2000 bytes into kilobytes using the AQA rule. What do you do?
- Which of these is the smallest unit of data?
- In an AQA exam a student writes that one kilobyte is 1024 bytes. What is wrong with this?
Explain the units of data
Explain the units used to measure data and the AQA convention for converting between them.
- Explain what a bit and a byte are
- List the units in order from smallest to largest
- Explain the AQA rule that each step is 1000, not 1024