1. Exploring Computer Science – Lesson 2-5
Counting in Binary
Exploring Computer Science – Lesson 2-5

2. Let’s Play A Game
Click to add text

3. Journal Entry
How high can you count using 10 fingers?

4. Count the Dots Let’s look at how binary numbers work…
Look at this part of the Flippy Do:
Is there a pattern? What number comes next?
We can define the numbers as powers of 2? V

5. Numbers In Binary If I want to show the number 9 in binary
I need an 8
and 1
In binary that’s 1001!

6. Numbers In Binary If I want to show the number 6 in binary
I need an 4
and 2
In binary that’s 110!

7. Numbers In Binary If I want to show the number 19 in binary
I need an 16
and 2
and 1
In binary that’s 10011!

8. Examples Decimal to Binary
What is the binary number for the decimal number: 17
16+ 1 is 10001 25
is 11001 36 is

9. Examples Binary to Decimal
What is the decimal number for the binary number:
11100
is 28 1
1 is 1
100111
is 39

10. “Bits”
When we look at a decimal number we call each of numbers the “digits”: the ones digit, the tens digit, the hundreds digit, etc.
In computer science when we look at the binary numbers we call those things “bits”
To represent numbers 0-7 I need 3 bits
111 = 7
To represent numbers 0-31 need 5 bits
11111 = 31

11. Your Turn… In your journal write:
The binary number for these decimal numbers:
2 =
14 =
31 =
The decimal number for these binary numbers:
1111 =
1010=
101=

12. Journal Entry Download “Lesson 2-5 - Secret Message” from the website.
In your journals, decode the secret message

13. What does this have to with computers???
Computers today use the binary system to represent information.
It is called binary because only two different digits are used. It is also known as base two (humans normally use base 10).
Each zero or one is called a bit (binary digit). A bit is usually represented in a computer’s main memory by a transistor that is switched on or off, or a capacitor that is charged or discharged.

14. What does this have to with computers???
When data must be transmitted over a telephone line or radio link, high and low-pitched tones are used for the ones and zeros.
On magnetic disks (floppy disks and hard disks) and tapes, bits are represented by the direction of a magnetic field on a coated surface, either North-South or South-North.

15. What does this have to with computers???
Audio CDs, CD-ROMs and DVDs store bits optically—the part of the surface corresponding to a bit either does or does not reflect light.

16. What does this have to with computers???
One bit on its own can’t represent much, so they are grouped together in groups of eight, which can represent numbers from 0 to 255. A group of eight bits is called a byte.
That’s were get the get the terms
Kilobyte (1,024 bytes * 8 = 8,192 bits)
Megabyte (1,048,576 bytes * 8 = 8,388,608 bits)
Gigabyte (1,073,741,824 bytes * 8 = 8,589,934,592 bits) – That’s a lot of bits!

17. What does this have to with computers???
Ultimately bits and bytes are all that a computer uses to store and transmit numbers, text, and all other information.

18. Try this out.. For the next 10 minutes play this game

19. Journal Entry
Imagine your fingers are “bits”. A finger that’s up is a “1” and a finger that is down is a “0”.
In your journals calculate how high you can count using the fingers on 1 hand and then using the fingers on both hands.

21. Rest of Today Individual Assignment
Download “Lesson More on Binary Numbers - Homework” from the website.
Complete both parts and turn it in.
Make sure you answer all the questions in each part fully and completely. Use complete sentences!
Turn this today.

22. For Question 2 – Limit it to just these keys…