Binary and Number Systems
What's covered
Key facts
0001 + 0001 = 0010 (1 + 1 = 2).
A bit (0 or 1) is the smallest unit of digital information.
Binary 0110 = 4 + 2 = 6 in decimal.
Decimal 0 = binary 00000000 (all bits off) in 8-bit.
Hexadecimal uses 16 distinct digit symbols (0–9 and A–F).
Binary digits (0/1) map directly onto Boolean logic (false/true) — making it natural for computers to use AND/OR/NOT gates to process binary data.
0011 + 0011 = 0110 (3 + 3 = 6).
One byte is exactly 8 bits.
Binary 10 = 2 + 0 = 2 in decimal.
Decimal 10 = binary 1010 (8 + 2), NOT binary 100.
Sample questions
A taste of the 66 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
What is 1 + 1 in binary?
- •01 with a carry
- ✓10 with a carry
- •11 with no carry
- •2 in binary notation
Which is largest?
- •Byte (just eight bits)
- ✓Gigabyte (about a billion bytes)
- •Kilobyte (about a thousand bytes)
- •Megabyte (about a million bytes)
What is binary 1010 in decimal?
- •Eight
- •Five
- ✓Ten
- •Twenty
What is decimal 5 in binary?
- •100 (just 4)
- ✓101 (4 + 1)
- •1010 (eight plus two)
- •111 (4 + 2 + 1)
How many bits does one hex digit represent?
- •Eight bits (one byte)
- ✓Four bits (one nibble)
- •One bit (a single bit)
- •Sixteen bits (two bytes)
What two states does binary use?
- •High, medium, and low
- •On, off, and standby
- •True and false only
- ✓Zero and one
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