Repeated Left-Shift and Add Algorithm - 3.5.1 | 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.

Initial Understanding of the Algorithm

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

Today, we will explore the Repeated Left-Shift and Add Algorithm. This method is essential for multiplying binary numbers by mimicking how we do this in decimal form. Does anyone know how multiplication works in decimal?

Student 1
Student 1

We multiply by adding shifted values based on the digits!

Teacher
Teacher

Exactly! In binary multiplication, we also create partial products, but we deal with bits. Who can tell me what happens when we identify a '1' in the multiplier?

Student 2
Student 2

We use the multiplicand as is and shift it!

Teacher
Teacher

Good job! Let's remember that rule with the acronym 'M'so P'shift', which stands for 'Multiply'so Partially Shifted'. Let's continue to dig deeper into how we align these partial products.

Creating Partial Products

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

Now, let's consider our multiplicand. If we have a multiplier of 110, what would our first step be?

Student 3
Student 3

We start with the LSB, which is '0', so we'd create a row of zeros.

Teacher
Teacher

That's correct! We wouldn't add anything from that first bit. Moving to the next bit, which is a '1', what does that mean?

Student 4
Student 4

We take the multiplicand and keep it; then we shift it for the next round!

Teacher
Teacher

Right! So, remember to 'Shift Left and Keep Right!' Whenever you encounter a '1', keep the multiplicand. Now, let's add these partial products together.

Adding Partial Products

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

In our last session, we've left some partial products after shifting. How do we finalize our calculation?

Student 1
Student 1

We add all the partial products together to get the final result!

Teacher
Teacher

Excellent! We need to be precise with our binary addition. So let's recap: each partial product gives us a piece of our final answer in binary. If our result comes from a signed multiplication, we need to check signsβ€”who remembers how that works?

Student 2
Student 2

If they have different signs, it’s negative, otherwise positive!

Teacher
Teacher

Well done! Let's reinforce that with the mnemonic 'Same's Positive, Diff's Negative'. Now, can anyone summarize what we learned today?

Introduction & Overview

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

Quick Overview

The Repeated Left-Shift and Add Algorithm is a method for multiplying binary numbers that involves creating partial products by shifting and adding.

Standard

This section discusses the Repeated Left-Shift and Add Algorithm, a method used in binary multiplication. It explains how to obtain partial products by shifting the multiplicand based on the bits of the multiplier. Each partial product, if derived from a '1' bit in the multiplier, is added up to achieve the final product.

Detailed

Repeated Left-Shift and Add Algorithm

In digital arithmetic, the Repeated Left-Shift and Add Algorithm is a systematic approach to multiplying binary numbers. The essence of this method is to generate partial products by multiplying the multiplicand (the number being multiplied) with individual bits of the multiplier (the number that is multiplying). For each '1' bit found in the multiplier, a shifted version of the multiplicand is produced. The steps involved in this method are as follows:

  1. Identify the LSB: Start with the Least Significant Bit (LSB) of the multiplier.
  2. Create Partial Product: If the LSB is '1', the multiplicand is copied as the partial product; if it is '0', the partial product is a series of '0's.
  3. Shift: Each subsequent partial product is derived by shifting the previous one to the left by one position.
  4. Add: All partial products are then added together to form the final product.
  5. Sign Management: If the multiplicand and multiplier have different signs, the product is negative; otherwise, it is positive.

The importance of the Repeated Left-Shift and Add Algorithm lies in its systematic approach, mirroring traditional decimal multiplication but suited for binary operations, facilitating efficient computation in digital systems.

Youtube Videos

Introduction to Number Systems
Introduction to Number Systems

Audio Book

Dive deep into the subject with an immersive audiobook experience.

Overview of the Algorithm

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

In the β€˜repeated left-shift and add’ method of binary multiplication, the end-product is the sum of several partial products, with the number of partial products being equal to the number of bits in the multiplier binary number. This is similar to the case of decimal multiplication.

Detailed Explanation

The repeated left-shift and add algorithm multiplies binary numbers by breaking down the process into a series of simpler steps, known as partial products. These partial products are then added together to obtain the final result. Each multiplicand in binary is shifted left for each bit of the multiplier, thereby simulating the decimal multiplication where you shift the numbers down for each column (placed in increasing order of place value).

Examples & Analogies

Consider how you might multiply 23 by 6 using the traditional method: you write 6 in one column and then multiply it by each digit of 23 while shifting your position down (for example, multiplying by 3 and then by 20). This approach is like stacking boxes; you keep adding more boxes as you get more digits from your multiplication, meaning that the final result is just the total height of all the stacked boxes (partial products) when added together.

Generating Partial Products

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Each successive partial product after the first is shifted one digit to the left with respect to the immediately preceding partial product. In the case of binary multiplication too, the first partial product is obtained by multiplying the multiplicand binary number by the LSB of the multiplier binary number.

Detailed Explanation

For each bit in the multiplier (starting from the least significant bit, LSB), you compute a partial product. If the LSB is '1', the partial product is simply the multiplicand; if it is '0', the partial product is all '0's. Then, for every successive bit, you shift the previous partial product one position to the left. This simulates multiplying by 10 in decimal, where each shift represents increasing the place value.

Examples & Analogies

Imagine you're stacking blocks to create a tower. Every time you add a new level to your tower (representing a higher bit), you shift the previous levels over to make space. For instance, if you first set down a large base (the multiplicand) for the LSB of the multiplier, you shift that base farther left with each new level depending on whether the bit is '1' (you keep it) or '0' (you don't put a block there). The total height of your tower will represent the final answer.

Handling the Most Significant Bit (MSB)

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

We proceed towards the MSB of the multiplier and obtain various partial products. The second partial product is shifted one bit position to the left relative to the first partial product; the third partial product is shifted one bit position to the left relative to the second partial product and so on.

Detailed Explanation

As you work leftwards in the multiplier from the LSB to the MSB, each new bit will determine whether a new partial product is added or not. This means each position in binary is equivalent to a power of 2, and shifting left effectively multiplies the number by 2. Each resulting partial product's place value increases accordingly, ensuring correct addition of partial sums at the end.

Examples & Analogies

Think of comparing the growth of a tree over time; as seasons change (representing each binary bit position), the tree can 'grow' by adding rings (partial products) which are pushed further out (shifted left). When you measure its total height after a few years (adding all the partial products), you see how all those seasons contributed to its current stature.

Final Addition of Partial Products

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

The addition of all partial products gives the final answer. If the multiplicand and multiplier have different signs, the end result has a negative sign; otherwise it is positive.

Detailed Explanation

After generating all the relevant partial products through shifts and multiplications based on the bits of the multiplier, these are added together like in traditional arithmetic. If the inputs had different signs (one positive and one negative), the final result would be negative. If they were the same, the result would be positive.

Examples & Analogies

Imagine you're running a race and you have friends cheering you on (positive signs) or detractors shouting against you (negative signs). The total support you feel at the finish line (final sum of all partial products) depends on whether more cheerers or detractors influenced your run. If you had a lot of positive cheers, you’d finish strong; if you were weighed down by negative shout-outs, your morale might suffer, leading to a different outcome.

Example Multiplication

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

The procedure is further illustrated by showing (23) Γ— (6) multiplication.

Detailed Explanation

For example, multiplying 23 (10111 in binary) by 6 (110 in binary) would involve calculating the partial products by checking each bit of 6. This leads to partial products as follows: for each 1 in the binary of 6, the full multiplicand is used and shifted appropriately. After calculating and summing those, you end up with the binary representation of 138.

Examples & Analogies

Think of it like cutting different lengths of fabric (the multiplicand) for sewing shirts (the multiplier), where for every shirt you make (1 in binary), you will use the entire length; but if you don’t make a shirt (0 in binary), you won’t cut any fabric. At the end of your work (addition), you’ll have a total length of fabric used for all your shirts, represented as the final result in binary.

Definitions & Key Concepts

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

Key Concepts

  • Partial Product: Contains the results of multiplication for each significant bit of the multiplier.

  • Left-Shift: Essential in the algorithm for shifting the position of binary digits to align for addition.

  • Sign Management: Understanding how to determine the final sign of the resultant product based on the multiplicand and multiplier.

Examples & Real-Life Applications

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

Examples

  • Example: Multiply (23) x (6) using repeated left-shift and add algorithm to illustrate binary product generation.

Memory Aids

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

🎡 Rhymes Time

  • Shift left, when you see one, // Add the products, the work is done!

πŸ“– Fascinating Stories

  • Imagine a chef (the multiplicand) baking a cake (the product). Every time a customer (a '1' in the multiplier) asks for a slice, the chef prepares one (creates a partial product) and shifts to prepare for the next customer.

🧠 Other Memory Gems

  • Remember to 'Count and Shift Left!' to complete the binary multiplication.

🎯 Super Acronyms

PSL - Partial Product, Shift Left.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Multiplicand

    Definition:

    The number that is being multiplied in a multiplication operation.

  • Term: Multiplier

    Definition:

    The number by which the multiplicand is multiplied.

  • Term: Partial Product

    Definition:

    The result of multiplying the multiplicand by a single bit of the multiplier.

  • Term: LeftShift

    Definition:

    The operation of moving all bits in a binary number to the left by one position.

  • Term: Binary Multiplication

    Definition:

    A mathematical operation in which two binary numbers are multiplied together.