Would you like to know more about 2 's complement subtraction for kids? Well, then, you've come to the right place! This article will cover a 2's complement and how it works in subtraction with complements. Two binary numbers can be subtracted using the approach of the second complement. By the end of this article, you should be more confident with your ability to perform 2 's complement subtraction, including binary subtraction using 2's complement. Let's get started!
What is a 2 's Complement?
To implement this method for subtracting two binary numbers, the first step is to find the 2’s complement of the number to be subtracted from another number. To get the 2’s complement, first of all, 1’s complement is found, and then 1 is added. The addition is the required 2’s complement.
Suppose we need to find the 2’s complement of the binary number 10010. First, find 1’s complement. To find this, replace all 1 to 0 and all 0 to 1. Therefore, 1’s complement of 10010 will be 01101. Add 1 to this, and we will get the 2’s complement, i.e. 01110.
Binary Subtraction Using 2's Complement
To learn how to subtract binary numbers using 2's complement, which is the subtraction of a smaller number from a larger number using 2’s complement subtraction, the following steps are to be followed:
Step 1: Determine the 2’s complement of the smaller number
Step 2: Add this to the larger number.
Step 3: Omit the carry. Note that there is always a carry in this case.
The following example illustrates the above-mentioned steps:
Exampe: Subtract $(1010)_2$ from $(1111)_2$ using 2's complement method.
Ans:
Step 1: 2's complement of $(1010)_2$ is $(0110)_2$.
Step 2: Add $(0110)_2$ to $(1111)_2$.
This is shown below:
Subtract Using 2's Complement Method
To subtract a larger number from a smaller number using 2’s complement subtraction, the following steps are to be followed:
Step 1: Determine the 2’s complement of the smaller number.
Step 2: Add this to the larger number.
Step 3: There is no carry in this case. The result is in 2’s complement form and is negative.
Step 4: To get an answer in true form, take 2’s complement and change its sign.
Example: Subtract $(1010)_2$ from $(1000)_2$ using 2's complement.
Ans:
Step 1: Find the 2's complement of $(1010)_2$. It is $(0110)_2$.
Step 2: Add $(0110)_2$ to $(1000)_2$.
2’s complement
Step 3 and Step 4 have been explained in the above difference calculation.
Subtraction Using r's Complement:
Let's say you want to subtract the number 01010100 from 11100011. We can do this using 2 's complement by simply doing the subtraction using r's complement.
Steps to Find r's Complement:
To find r's complement, add 1 to the calculated ($r-1$) 's complement.
Here is an example:
Q. Find the 7's and 8's complement of the number $(5 63)_8$
Step 1: Identify the base (or) radix. Here $r=8$.
Step 2: Since 7 is the largest digit in the number system, subtract each digit of the given number from 7, i.e. if it's a three-digit number, subtract the number from 777.
$\therefore(214)_8$ is the 7's complement of a given number
Step 3: To find r's complement, i.e. 8's complement, then add ' 1 ' to the result of 7 's complement number.
$\therefore(215)_8$ is the 8 's complement of the given number.
Solved Examples
Q 1. 10110 - 11010
Ans: 11010 has a 2s complement of (00101+1) or 00110.
Add the 2's complement to the minuend (10110+00110) or 11100.
Now taking its complement;
The solution is (00011+1)= - (00100)
Q 2. 10110-01111
Ans: 01111's 2s complement is 10001.
The minuend plus the complement of two (10110-10001) equals 100111.
The response is 00111.
Q 3. 0100-11101
Ans: 11101's 2s complement is 00011
The minuend plus the complement of two (10100- 00011) equals 10111.
Since there is no carry here, the response is 01001.
Q 4. 110101 - 101001
Ans: 101001's complement in 2 is 010111
(110101-010111) Add the minuend and the 2's complement to get 1001100.
Carry, the result's leftmost bit is a 1 and is ignored.
The response is 001100.
Practice Questions
Q 1. 1001 - 0100
Ans: 0101
Q 2. 0100 - 1011
Ans: 1011
Q 3. 0110 - 0100
Ans: 0010
Q 4. 10110- 11101
Ans: 00111
Q 5. 110-101
Ans: 001
Summary
In conclusion, in this article, we went over two's complement subtraction. We've done an example problem to show you how it works and how it is performed on paper. The examples provided in this article are used for demonstration purposes only and thus do not necessarily model the types of problems you would encounter on a standardised test.
Instead of simply memorising the steps in this article, you should practice the problems. You can choose to use paper and pencil or use a calculator, 2 's complement subtraction calculator, or your fingers on your smartphone. Therefore, if you want to perform division (and thus subtraction) without using r's complement, you will need to learn how to use 2 's complement while performing division.
