The Interactive Binary Lesson!

Learn binary addition and ASCII. This is a 15-20 minute interactive lesson.

Part 1: The Rules of Addition (2 mins)

To add binary numbers, you add one column at a time (right to left), just like in decimal. There are 5 simple rules to remember.

The 5 Rules:

  • Rule 1: 0 + 0 = 0
  • Rule 2: 0 + 1 = 1
  • Rule 3: 1 + 0 = 1
  • Rule 4: 1 + 1 = 0, Carry 1
  • Rule 5: 1 + 1 + 1 = 1, Carry 1

Worked Example:

Let's add 0011 (3) + 1000 (8):

  C  
  0011
+ 1000
  1011

Result: 1011 (which is 8 + 2 + 1 = 11). It works!

Part 2: 4-Bit Addition (5 mins)

Add the numbers. Type your answer in the box. Your answer might be 5 bits!

Part 3: 8-Bit Addition (5 mins)

Same rules, just more bits! These are harder. Your answer might be 9 bits!

Part 4: Binary Puzzles (Drag & Drop)

Now for a challenge! Drag the numbers to solve the puzzles.

0110
0010
0100
1000
Drop two numbers here
1000
0111
0110
0101
Drop two numbers here
0001
0011
0101
0100
Drop two numbers here
1000
0111
0110
1001
Drop two numbers here
0011
0100
0110
0101
Drop two numbers here

Part 5: ASCII Decoding (5 mins)

Computers store text as numbers using ASCII. Use the tables to decode the 3-letter binary messages.

DenaryBinaryCharacter
660100 0010'B'
690100 0101'E'
890101 1001'Y'

0100 0010 0101 1001 0100 0101

DenaryBinaryCharacter
650100 0001'A'
670100 0011'C'
840101 0100'T'

0100 0011 0100 0001 0101 0100

DenaryBinaryCharacter
680100 0100'D'
710100 0111'G'
790100 1111'O'

0100 0100 0100 1111 0100 0111

DenaryBinaryCharacter
780100 1110'N'
820101 0010'R'
850101 0101'U'

0101 0010 0101 0101 0100 1110

DenaryBinaryCharacter
750100 1011'K'
830101 0011'S'
890101 1001'Y'

0101 0011 0100 1011 0101 1001

Part 6: Complex ASCII Decoding (5 mins)

You will need a full ASCII table for this section. Decode the messages.

0100 0001 0100 0011 0100 0101

0101 1010 0100 1001 0101 0000

0100 1101 0100 0001 0101 1000

0100 0011 0100 1111 0100 0100 0100 0101

0100 0010 0101 1001 0101 0100 0100 0101

Part 7: Overflow Errors & Concepts (5 mins)

What happens when the answer is too big? An 8-bit number can only hold values up to 255 (which is 1111 1111). If the answer is 256 or more, it causes an Overflow Error because the 9th bit has nowhere to go!

Hint: The answer is 9 bits long (1 1000 1011). An 8-bit computer can't store it!

Lesson Complete!

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