Short Trick to find LCM using Co-Prime Numbers Concept

Duration: 9 min

This video lesson is available to enrolled students.

Return to /learn/RSSB-INFORMATICS-ASSISTANT/numerical-ability-problem-solving/hcf-lcm/finding-lcm/asset-short-trick-to-find-lcm-using-co-prime-numbers-concept after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. Numerical Ability & Problem Solving: Speed Mathematics and Basic Mathematics, Arithmetic, Number System, HCF LCM, Divisibility Rules, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Mixture and Alligation, Time and Work, Pipe and Cistern, Speed Time and Distance, Age Problems, Partnership, Data Interpretation, Mental Ability, Sequence and Series (Series), Powers and Exponents (Surds and Indices), Algebra, Statistics, Logarithm, Mensuration and Geometry, Permutation and Combination, Probability, Sequences and Series, Powers, Surds and Logarithms, Subject-Verb Agreement, Sentence Completion, Geometry, Sentence Structure and Correction, Data Sufficiency, Trigonometry, Measurement and Quantity Take-Off, Signal Space and Optimum Detection, Probability, Statistics, Algebra, Time and Work, Speed, Time and Distance, Data Interpretation, Combinatorics
  2. Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Directions (Direction Test), Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Logical Sequence Of Words, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence, Selection Decision Table (Decision Making), Alphabet and Word Tests, Numerical Reasoning, Number System, Averages, Mixtures and Alligation, Percentages, Series Completion, Analogy and Classification, Patterns in Two-Dimensional Figures, Coding and Decoding, Mathematical Operations, Direction Sense, Logical Deduction and Induction, Syllogisms and Venn Diagrams, Critical Reasoning, Order, Ranking and Sequence, Reading Comprehension, Profit, Loss and Discount, Constraint Puzzles, Traverse Surveying, Ratio and Proportion, Mensuration, Permutations and Combinations, Clocks and Calendars, Assembling and Grouping of Shapes, Transformation of Shapes, Three-Dimensional Patterns and Visualization, Cubes and Dice, Vocabulary, Blood Relations
  3. General Knowledge & Current Affairs (India + Rajasthan): History, Geography, Polity, Indian Economy, Static General Knowledge, State Wise GK, GK- Current Affairs, Environment, Physics
  4. Computer Fundamentals & Operating Systems: Basics of COA, Floating Point Rep, Digital Systems & Boolean Basics, Number Representation, Number System, Introduction to OS, File Management, Windows OS, Unix OS, Linux OS, Register Transfer and Microoperations, Virtual Memory
  5. Computer Networks: Introduction to CN, Data Communication, DLL: Error Control, DLL: Access Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Application Layer, Hardware Basics, Network Security
  6. Cyber Security: Cyber Threats and Malware Attacks, Role of Internet and Web Services, Security in Mobile and Wireless Computing, Electronic Data Interchange and E-Commerce, Physical Security and Cryptography Basics, Intrusion Detection Systems (IDS), Cyber Safety and Security, Ethical Hacking
  7. Programming (C & OOP): C Fundamentals, Control Flow, Arrays & Pointers, Functions, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, OOPS with C++, Operators & Expressions, Sorting Algorithms, Java Fundamentals, Java
  8. MS Office & Data Processing: MS Office Applications, Basics of DBMS
  9. Internet & Web Technology: Society, Law & Ethics, Terms & Abbreviations, Keyboard Shortcuts, Emerging Tech Trends, Artificial Intelligence, Emerging Technologies, Internet Fundamentals, Website, Browser & Services, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video, presented by Yash Jain from Knowledge Gate Eduventures, provides a comprehensive lesson on finding the Least Common Multiple (LCM) using the concept of co-prime numbers. The lecture begins with an introduction to the topic, followed by a clear definition of co-prime numbers, stating that any two consecutive numbers (e.g., 12 and 13) and any two prime numbers are co-prime. The core principle is established: the LCM of two co-prime numbers is simply their product. The video then demonstrates this rule through a series of worked examples. The first example, LCM(7, 10, 13), shows that since these numbers are co-prime, their LCM is 7 × 10 × 13 = 910. The second example, LCM(12, 18), illustrates a different method: first, the Highest Common Factor (HCF) is found to be 6, and the numbers are divided by it to get a co-prime pair (2, 3). The LCM is then calculated as HCF × (co-prime pair product) = 6 × 6 = 36. The final example, LCM(48, 72), reinforces the method by showing the HCF is 24, leading to a co-prime pair (2, 3), and the LCM is 24 × 6 = 144. The video concludes with a thank you message.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a title card displaying 'LCM & HCF' against a digital, data-stream background. It then transitions to a classroom setting with a cartoon teacher and a live instructor, Yash Jain. The main topic is introduced as 'Least Common Multiple (LCM)' on a green chalkboard. The instructor, visible in a small window, begins the lesson by explaining the concept of LCM and HCF, setting the stage for a detailed explanation of a shortcut method.

  2. 2:00 – 5:00 02:00-05:00

    The video focuses on a slide titled '5. LCM using Co-prime Numbers'. The instructor explains that any two consecutive numbers (e.g., 12 and 13) and any two prime numbers are co-prime. The key rule is highlighted: 'Product of two co-prime numbers = LCM'. The instructor emphasizes that when numbers have no common factor, their LCM is their product. This concept is demonstrated with the example LCM(7, 10, 13), where the numbers are shown to be co-prime, and the LCM is calculated as 7 × 10 × 13 = 910.

  3. 5:00 – 8:47 05:00-08:47

    The instructor presents a second method for finding LCM using co-prime numbers. The example LCM(12, 18) is used. The HCF of 12 and 18 is found to be 6. The numbers are divided by the HCF to get a co-prime pair (2, 3). The LCM is then calculated as HCF × (product of co-prime pair) = 6 × 6 = 36. This method is reinforced with a third example, LCM(48, 72), where the HCF is 24, leading to a co-prime pair (2, 3), and the LCM is 24 × 6 = 144. The video concludes with a 'THANKS FOR WATCHING' screen.

The video presents a clear, step-by-step progression on a specific mathematical shortcut. It starts by defining the core concept of co-prime numbers and establishing the fundamental rule that their LCM is their product. This is then applied to a simple case of three co-prime numbers. The lesson then advances to a more complex scenario, demonstrating a two-step method for numbers that are not co-prime: first, find the HCF, then divide the numbers by the HCF to create a co-prime pair, and finally, multiply the HCF by the product of the co-prime pair. This synthesis of the HCF and co-prime concepts provides a powerful and efficient technique for calculating the LCM.

Loading lesson…