This document provides an introduction to the binary number system used by computers. It explains that binary uses only the digits 0 and 1 to represent numbers, unlike the base-10 system that uses 0-9. It shows how each position in a binary number represents powers of 2, with the rightmost position being 20= 1, and each place to the left being twice the value. The document then demonstrates how to write different numbers like 9, 10, 18, and 33 in binary notation. It also explains that only 0s and 1s can be used and that odd and even numbers in binary can be determined by counting the 1s. Finally, it asks if numbers over 100 can be represented in binary.

1. An
introducti
on to
Binary

2. Binary is the language
used by computers.
It uses 0 and 1 to
represent different
numbers.

3. In the everyday number
system we use 0 – 9 to
show numbers.
H T U
5 6 9
If a number has two whole
numbers to its right we
know that it has a
‘hundreds’ value. In this
example the ‘5’ actually
represents 500.

4. Binary uses ‘Base 2’.
Each position to the
left is worth 2x more
than the place to the
right:
16 8 4 2 1
x2 x2 x2 x2
Of course you don’t have
to write in 1,2,4 etc.
You just remember them
like you remember HTU.

5. How do I write
numbers in
binary, Binary-
Bot?

6. To write numbers in Binary you only
have to be able to add.
For example:
If I wanted to write 9 as a Binary
number I have to see which columns I
can use to get to 9
16 8 4 2 1
1 0 0 1
I would put a 1 in the place that has
the value of ‘8’, zeroes in the ‘4’ and
‘2’ columns and a 1 in the ‘1’ column.
(1 x 8) and (1 x 1) gives me 9

7. But couldn’t I get to 9 like
this, Binary-Bot?
16 8 4 2 1
4 1
Or like this?
16 8 4 2 1
1 2 1
(1 x 4) and (2x2) and (1x1)
will give me a 9!

8. No!
Binary only uses 1s and 0s.
Here are some more examples:
32 16 8 4 2 1
1 0 1 0 = 10
1 0 0 1 0 = 18
1 0 0 0 0 1 = 33
Ah! I see
now!

9. 1 0 1 1
1 0 0 0 1
1 0 1 1 0
1 0
1 1 1 1 1 1
1 0 1 0 1 0
1 0 1 1 1
Can you
tell
straight
away
which
numbers
will be
odd?
Try working out these numbersHere are the answers
11
17
22
2
63
42
23

10. You can easily count from 1 – 10 using
the base 10 system – but could you do
this in Binary?
Here are the first three numbers to get
you started:
0 0 0 011

11. Yes! I just need to ‘add’
another column to the left.
64 32 16 8 4 2 1
1 1 1 1 1 0 1
This would give me 125!
Can you make numbers
over 100 in Binary?

12. That was
An
introducti
on to
Binary