Addition

Binary Addition

Binary is being able to add two numbers together but are represented in binary form, which consist of 1s and 0s

There are four possibilities when adding binary numbers, these possibilities are:

a total of 0 (0+0) put down 0
a total of 1 (1+0, 0+1 or 0+0+carried 1) put down 1
a total of 2 (1+1) put down 0, carry 1
a total of 3 (1+1+ carried 1) put down 1, carry 1

For example, solve 6+7 using binary addition:

First convert 6 and 7 from denary to binary using your preferred method

6 = 4+2+0 = 110
7 = 4+2+1 = 111

Then add them keeping in mind the 4 possibilities and add each digit together, starting on the right:

110  +
111

So:

0+1 = 1

1+1 = 0 carry 1

1+1+ carried 1 = 1 carry 1

1 + 0 = 1

so 110+111 = 1101. Converting this number back to denary gives us an answer of 13.

Another Example

Adding More Numbers Together

You could get 3 numbers to add however you wont be given a situation in which there are more than a total of 3.

For example:

101

101

011+

Which would = 1101

Adding Binary Numbers Into Denary

There are many ways to add two binary numbers together and get a denary value as the answer. The two main ways of doing are as follows: Method 1, Calculate the denary value of each binary number then add the two denary values together, you then should have the answer in denary. Or Method 2 which is just as simple. Add the two binary numbers together using 8-bit binary addition, then convert your binary answer into denary.

Revision

1.

What is 00110101 + 01010001 in binary?

→ 1+1 = 2. Put down o, carry 1

→ 0+0+1 = 1. Put down 1, carry 0

→ 1+0 = 1. Put down 1, carry 0

→ 0+0 = 0. Put down 0 carry 0

→ 1+1 = 2. Put down 0, carry 1

→ 1+0+1 = 2. Put down 0, carry 1

→ 0+1+1 = 2. Put down 0, carry 1

→ 0+0+1 = 1. Put down 1, carry 0

→ 10000110

2.

What is 01110001 + 00011111 in denary?

→ 1+1 = 2. Put down 0, carry 1

→ 0+0+1 = 1. Put down 1, carry 0

→ 0+0 = 0. Put down 0, carry 0

→ 0+0 = 0.Put down 0, carry 0

→ 1+1 = 2. Put down 0, carry 1

→ 1+0+1 = 2. Put down 0, carry 1

→ 1+1+1 = 3. Put down 1, carry 1

→ 0+0+1 = 1. Put down 1, carry 0

→ 11000010

→ 128+64+2 = 194

3.

What is 01101110 + 01100101 in 8-bit binary?

→ 0 + 1 = 1. Put down 1, carry 0.

→ 1 + 0 = 1. Put down 1, carry 0.

→ 1 + 1 = 2. Put down 0, carry 1.

→ 0 + 1 + 1 = 2. Put down 0, carry 1.

→ 0 + 0 + 1 = 1. Put down 1, carry 0.

→ 1 + 1 = 2. Put down 0, carry 1.

→ 1 + 1 + 1 = 3. Put down 1, carry 1.

→ 0 + 0 + 1 = 1. Put down 1, carry 0.

→ 11010011

4.

What is it called when the numbers adds together to make a number bigger than 255 so doesn't fit into the 8 bits?

→ This is an overflow.

5. What do you do when you have an overflow?

	Add it anyway and then forget the overflow
	Add an extra bit
	give up
	Subtract the numbers instead

6.

What is 01100010 + 01001101 in 8 bit binary?

→ Add the one no carry

→ Add the one no carry

→ Add the one no carry

→ Add the one no carry

→ Don't add anything because its zero

→ Add the one no carry

→ Add the one carry the 1

→ Add the carry to the 0's so its a 1

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