## How do you subtract in BCD?

Method of BCD Subtraction : 1

- At first 1’s compliment of the subtrahend is done.
- Then the complimented subtrahend is added to the other number from which the subtraction is to be done.
- Now in BCD Subtraction there is a term ‘EAC(end-around-carry)’.
- In the final result if any carry bit occurs the it will be ignored.

## Which complementation is used to performing BCD subtraction?

The BCD Subtraction using 10s Complement can be used to perform subtraction by adding the minuend to the 10s Complement of the subtrahend and dropping the carry.

**How do you find 10s complement of BCD?**

10’s complement of a decimal number can be found by adding 1 to the 9’s complement of that decimal number. It is just like 2s complement in binary number representation. For example, let us take a decimal number 456, 9’s complement of this number will be 999-456 which will be 543. Now 10s complement will be 543+1=544.

### Why do we add 6 in BCD?

When you do math in decimal, if a number is larger than 10 you need to take the modulus of 10 and carry to the next row. Similarly, in BCD math, when the result of the addition is larger than 9 you add 6 to skip the 6 remaining “invalid” values and carry to the next digit.

### How do you write BCD?

The BCD stands for Binary Coded Decimal Number. In BCD code, each digit of the decimal number is represented as its equivalent binary number….Example 1: (11110) 2.

Binary Code | Decimal Number | BCD Code |
---|---|---|

0 0 1 0 | 2 | 0 : 0 0 1 0 |

0 0 1 1 | 3 | 0 : 0 0 1 1 |

0 1 0 0 | 4 | 0 : 0 1 0 0 |

0 1 0 1 | 5 | 0 : 0 1 0 1 |

**What is valid BCD number?**

Binary Coded Decimal (BCD) code BCD is a way to express each of the decimal digits with a binary code. In the BCD, with four bits we can represent sixteen numbers (0000 to 1111). But in BCD code only first ten of these are used (0000 to 1001). The remaining six code combinations i.e. 1010 to 1111 are invalid in BCD.

#### Why BCD is used?

BCD was commonly used for displaying alpha-numeric in the past but in modern-day BCD is still used with real-time clocks or RTC chips to keep track of wall-clock time and it’s becoming more common for embedded microprocessors to include an RTC. It’s very common for RTCs to store the time in BCD format.

#### How to do BCD or binary coded decimal subtraction?

BCD or Binary Coded Decimal | BCD Conversion Addition Subtraction. BCD or Binary Coded Decimal is that number system or code which has the binary numbers or digits to represent a decimal number. A decimal number contains 10 digits (0-9). Now the equivalent binary numbers can be found out of these 10 decimal numbers.

**How is the complimented subtrahend added in BCD?**

Then the complimented subtrahend is added to the other number from which the subtraction is to be done. This is called adder 1. Now in BCD Subtraction there is a term ‘EAC (end-around-carry)’. If there is a carry i.e if EAC = 1 the result of the subtraction is +ve and if EAC = 0 then the result is –ve. A table shown below gives the rules of EAC.

## How to add two numbers to a number in BCD?

Now, using ordinary BCD addition rules we add the two numbers. 10’s complement of 0101 0110 is 0100 0100 (subtracted 9 from each 4 bit segment and added a 1 to the last one. Notice that this could overflow when finding the 10’s complement of 0000.

## Is the result of addition greater than 9 in BCD?

In case 1 the result of addition of two binary number is greater than 9, which is not valid for BCD number. But the result of addition in case 2 is less than 9, which is valid for BCD numbers.