Addition and Subtraction - 3.7.1 | 3. Digital Arithmetic - Part B | Digital Electronics - Vol 1
K12 Students

Academics

AI-Powered learning for Grades 8–12, aligned with major Indian and international curricula.

Academics
Professionals

Professional Courses

Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.

Professional Courses
Games

Interactive Games

Fun, engaging games to boost memory, math fluency, typing speed, and English skillsβ€”perfect for learners of all ages.

games

Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Introduction to Excess-3 Code

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

Excess-3 code is used for BCD representation. To convert a BCD number, we simply add '0011' to each 4-bit group. Can anyone tell me the excess-3 equivalent of the BCD for the number 5?

Student 1
Student 1

That would be 1000, right?

Teacher
Teacher

That's incorrect. Remember, BCD for 5 is 0101, so adding '0011' gives us 1000. Now, what do we need to remember when adding these numbers?

Student 2
Student 2

We should also look out for carries and how to adjust the result.

Teacher
Teacher

Exactly! This understanding is crucial. Let's move on to the addition process!

Steps in Addition

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

The steps for excess-3 addition are straightforward. We convert BCD numbers to excess-3 codes, then add them. If there's a carry, we adjust accordingly. Can anyone restate the steps?

Student 3
Student 3

Convert to excess-3, perform binary addition, adjust if there’s a carry, and get the result!

Teacher
Teacher

Well done! Let's explore an example. If we add 356 and 579 in BCD, what should the first step be?

Student 4
Student 4

We need to convert 356 and 579 to excess-3.

Teacher
Teacher

Correct! And after the addition of their excess-3 forms, how do we know what to adjust for?

Student 1
Student 1

We look at the results of each of the four-bit groups and see if there's a carry.

Subtraction Process

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

Now, let’s talk about how to subtract BCD numbers using excess-3. Can anyone summarize the essential steps?

Student 2
Student 2

We first convert both numbers to excess-3, perform binary subtraction, and adjust if needed!

Teacher
Teacher

Yes! Specifically, we need to subtract β€˜0011’ from any invalid groups and handle borrows correctly. Why is post-adjustment so important?

Student 3
Student 3

Because we want to ensure the result is still a valid BCD number!

Teacher
Teacher

Perfect! Let's delve into an example of subtracting 8 from 185.

Working Through Examples

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

For the example of (185) - (8), what is the first step?

Student 4
Student 4

We convert them to excess-3. Thus, 185 becomes 0100 1011 and 8 becomes 0011 0011.

Teacher
Teacher

Excellent! Now, after performing the binary subtraction, how do we know we need adjustments?

Student 1
Student 1

If we encounter any invalid groups or if a borrow occurs.

Teacher
Teacher

Exactly! Making this distinction is crucial to derive the correct BCD result. Let’s work through the binary step together.

Verifying Results

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

After performing addition and subtraction, how do we verify our excess-3 results?

Student 2
Student 2

We convert back to BCD and then check if the decimal equivalent makes sense!

Teacher
Teacher

Yes, a great way to confirm accuracy. Why is checking the decimal conversion necessary?

Student 3
Student 3

To ensure we did everything right during the calculations.

Teacher
Teacher

Great insights! Remember, all calculations should lead back to expected decimal outcomes.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section explores the methods of performing addition and subtraction of BCD numbers using excess-3 code.

Standard

Addition and subtraction of BCD numbers using excess-3 code involve converting BCD into excess-3 format, performing binary addition or subtraction, and then adjusting the results according to whether carries or borrows occur. This section details the steps for both operations and illustrates them with examples.

Detailed

Addition and Subtraction in Excess-3 Code

The section covers the methods for performing addition and subtraction of Binary Coded Decimal (BCD) numbers through the use of excess-3 code.

Key Points:

Excess-3 Code:

Excess-3 is a non-weighted code used to express decimal numbers. It is obtained by adding a binary number β€˜0011’ to the standard BCD representation.

Addition Process:

  1. Convert BCD numbers to excess-3 by adding β€˜0011’ to each 4-bit group.
  2. Perform binary addition on the converted excess-3 numbers.
  3. If any 4-bit group generates a carry, add β€˜0011’ to that group.
  4. If there is no carry in a group, subtract β€˜0011’ during adjustment.
  5. The result remains in excess-3 format.

Subtraction Process:

  1. Convert both minuend and subtrahend to excess-3 code.
  2. Perform binary subtraction.
  3. For invalid BCD codes, subtract β€˜0011’ from these groups.
  4. If a borrow occurs, adjust the respective group by also subtracting β€˜0011.’
  5. Add β€˜0011’ to any remaining valid groups to yield the final result in excess-3.

The section is further exemplified through detailed calculations, demonstrating how both addition and subtraction yield expected decimal results.

Youtube Videos

Introduction to Number Systems
Introduction to Number Systems

Audio Book

Dive deep into the subject with an immersive audiobook experience.

Floating-Point Representation of Numbers

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

If N1 and N2 are two floating-point numbers given by N1 = m1 Γ— 2^e1 and N2 = m2 Γ— 2^e2, then:

Detailed Explanation

In floating-point arithmetic, numbers are represented in a format where 'm' is the mantissa and 'e' is the exponent. This allows for the representation of a very wide range of values. For example, a number like 39 can be expressed as 0.100111 Γ— 2^6, which means '0.100111' with an exponent of '6'. Essentially, the exponent adjusts the scale of the number.

Examples & Analogies

Think of how scientific notation works in regular decimal numbers (like 3.1 Γ— 10^2 for 310). In floating-point arithmetic, we do something similar by separating the significant digits (mantissa) from the scaling factor (exponent).

Addition of Two Floating-Point Numbers

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

N1 + N2 = (m1 + m2) Γ— 2^e

Detailed Explanation

When adding two floating-point numbers, if they have the same exponent, you add the mantissas directly and keep the exponent the same. If their exponents are different, you must first align the numbers by adjusting the exponent of one of them, typically by shifting the mantissa to the right and increasing the exponent until both exponents match. Finally, you carry out the addition on the aligned mantissas.

Examples & Analogies

Imagine filling two different-sized cups with water. To combine them, you can’t just pour both into a single cup without making sure their levels are compatible. Similarly, in addition of floating-point numbers, first dissolve any mismatch in exponents before you mix them together.

Subtraction of Two Floating-Point Numbers

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

N1 - N2 = (m1 - m2) Γ— 2^e

Detailed Explanation

The subtraction operation works similarly to addition. You start by ensuring both numbers are using the same exponent. If N1 is greater than N2, you perform the subtraction directly on their mantissas after aligning them. If the subtraction results in a negative mantissa, you would need to handle it by potentially normalizing the result, meaning you may need to adjust both the mantissa and exponent to ensure it conforms to the proper floating-point representation.

Examples & Analogies

Imagine you are measuring heights of two buildings with different scales. Before determining the height difference, you need to convert them to the same units. This means proper scaling (or aligning), just like ensuring the correct exponent before performing subtraction in floating-point numbers.

Post-Normalization

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Post-normalization of the result may be required after the addition or subtraction operation.

Detailed Explanation

Post-normalization is a crucial step where after performing addition or subtraction, the result might not fit into the standard floating-point format. For example, the mantissa might need to be adjusted again to fit within its expected limits, and the exponent may have to be incremented or decremented accordingly. This ensures that the result adheres to the floating-point representation conventions.

Examples & Analogies

It’s similar to adjusting the height of a container to fit a specific shelf. After combining ingredients in a bowl, you check to ensure it fits into your container correctly. If the mixture is too high, you may need to level it off or transfer some out to avoid spilling, ensuring everything is tidy and fits perfectly.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Excess-3 Code: A method to represent BCD numbers by adding 3.

  • Carry and Borrow: Key operations involved in addition and subtraction.

  • Binary Addition/Subtraction: Fundamental operations utilized in the calculation processes.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • Addition Example: Adding BCD 356 and 579 via excess-3 gives 935 in decimal.

  • Subtraction Example: Subtracting 8 from 185 results in 177 through the excess-3 method.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎡 Rhymes Time

  • To convert and add in excess-3, three's the key, can’t you see?

πŸ“– Fascinating Stories

  • Imagine the BCD numbers crossing the river (addition), and we need to give them '3' (excess-3) to safely make it to the other side without a carry!

🧠 Other Memory Gems

  • CASEL – Convert, Add, Subtract, Evaluate, and Look for adjustments.

🎯 Super Acronyms

BCA (Binary Convert Add) for remembering the steps in BCD operations.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Excess3 Code

    Definition:

    A non-weighted code used to express decimal numbers by adding 3 to each digit.

  • Term: BCD

    Definition:

    Binary-Coded Decimal, a class of binary encodings for decimal numbers.

  • Term: Carry

    Definition:

    An overflow that occurs in addition when a digit exceeds its base.

  • Term: Borrow

    Definition:

    A term in subtraction indicating that a value was taken from a higher order digit.