Demo: Divisibility Rules of 2, 3 and 4

Duration: 12 min

This video lesson is available to enrolled students.

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Inside: a video lesson and guided study material.

Module outline

  1. About the Course: About the Course
  2. Paper-1 & 2 | Basic Numeracy: अनुपात और समानुपात / Ratio and Proportion, Divisibility Rules, मिश्रण और एलिगेशन / Mixture and Alligation, Permutation and Combination, Logarithm, संख्या पद्धति / Number System, महत्तम समापवर्तक और लघुत्तम समापवर्त्य / HCF and LCM, अनुक्रम, श्रेणी और संयोजन / Sequences, Series and Combinatorics, समय, चाल और दूरी / Time, Speed and Distance, प्रतिशत / Percentage, औसत / Average, घन क्षेत्रमिति / Solid Mensuration, Age Problems, Arithmetic, Statistics, Probability, लाभ, हानि और बट्टा / Profit, Loss and Discount, साधारण और चक्रवृद्धि ब्याज / Simple and Compound Interest, Partnership, Speed Mathematics and Basic Mathematics, Algebra, सरलीकरण, घातांक और करणी / Simplification, Indices and Surds, समय और कार्य / Time and Work, Pipe and Cistern, RSSB Specific Videos - Basic Numeracy, समुच्चय, संबंध, फलन और विविक्त गणित / Sets, Relations, Functions and Discrete Mathematics, संख्या पद्धति और संख्या सिद्धांत / Number Systems and Number Theory, निर्देशांक ज्यामिति, सदिश और त्रिविमीय ज्यामिति / Coordinate Geometry, Vectors and 3D Geometry, बहुपद, समीकरण और सम्मिश्र संख्याएँ / Polynomials, Equations and Complex Numbers
  3. Paper-1 & 2 | Data Interpretation: आँकड़ा निर्वचन / Data Interpretation
  4. Paper-1 & 2 | General Mental Ability: Mental Ability, RSSB Specific Videos - Mental Ability
  5. Paper-1 & 2 | Logical Reasoning and Analytical Ability: श्रेणी / Series, कूट लेखन एवं कूट वाचन / Coding-Decoding, Data Sufficiency, अशाब्दिक तर्क / Non-Verbal Reasoning, Syllogisms, बैठक व्यवस्था एवं पहेलियाँ / Seating Arrangement and Puzzles, रक्त संबंध / Blood Relations, दिशा एवं दूरी / Direction and Distance, Analytical Reasoning (Counting Figures Reasoning), गणितीय संक्रियाएँ एवं लुप्त संख्या / Mathematical Operations and Missing Numbers, कैलेंडर एवं घड़ी / Calendar and Clock, Clock, घन, पासा एवं आकृतियों की गिनती / Cubes, Dice and Figure Counting, वेन आरेख, न्याय वाक्य एवं असमानता / Venn Diagrams, Syllogism and Inequalities, सादृश्यता एवं वर्गीकरण / Analogy and Classification, क्रम एवं रैंकिंग / Order and Ranking, कथन आधारित तार्किक विवेचन / Statement-Based Reasoning, Data Arrangement, वर्णमाला एवं संख्या परीक्षण / Alphabet and Number Test, Crypt Arithmetic
  6. Paper-1 & 2 | Decision Making and Problem Solving: आँकड़ों की पर्याप्तता एवं निर्णय क्षमता / Data Sufficiency and Decision Making
  7. Paper-1 | General Science: वैज्ञानिक उपलब्धियाँ और अनुसंधान / Scientific Achievements and Research, Biology, Chemistry, RSSB Specific Videos
  8. Paper-1 | General Awareness: राज्य विशेष सामान्य ज्ञान / State-Specific General Knowledge, समसामयिकी / Current Affairs
  9. Paper - 2 | Digital Logic Systems: Digital Systems & Boolean Basics, Logic Gates & Hardware, Combinational Circuit, Sequential Circuits
  10. Paper-2 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Calculus, Relational Algebra, SQL, NoSQL
  11. Paper-2 | Data Structures & Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Algorithm Analysis, Sorting Algorithms, Intro to Compilers, Hashing
  12. Paper 2 | Data Communication and Network Security: Introduction to CN, Data Communication, Data Link Layer - Ethernet, DLL: Error Control, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Application Layer, Hardware basics, Network Security, Ethical Hacking
  13. Paper-2 | Operating Systems: Introduction to OS, Process Management, Memory Management, File Management, Deadlock
  14. Paper-2 | Computer Organization and Architecture: Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations, Programming the Basic Computer, Number System, Number Representation
  15. Paper 2 | System Analysis and Design: Fundamentals of Systems and Information Systems, Fundamentals of Software Engineering, SDLC and Development Approaches, Software Documentation and Software Requirements Specification (SRS), SDD and Quality Assurance, Security, Risk Management & Maintenance, Software Testing
  16. Paper-2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  17. Paper 2 | OOPS , C++ , JAVA: Language Design, OOPS with C++, Java, .Net Programming, Java Fundamentals
  18. Paper 2 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  19. Emerging Trends and AI: Emerging Tech Trends, कंप्यूटर के मूल सिद्धांत / Computer Fundamentals, व्यापार, विपणन एवं उपभोक्ता संरक्षण / Trade, Marketing and Consumer Protection
  20. Paper-2 | Data Processing (Ms-Office): MS Office Applications, कंप्यूटर सॉफ़्टवेयर / Computer Software, ऑपरेटिंग सिस्टम / Operating System, वर्ड प्रोसेसिंग (MS Word) / Word Processing (MS Word), प्रेज़ेंटेशन (MS PowerPoint) / Presentation Software (MS PowerPoint)
  21. Paper-2 | Internet and Web Technologies: HTML Basics, CSS, XML, JavaScript-Basics, Internet Fundamentals, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, Terms & Abbreviations, Cyber Threats and Malware Attacks, Role of Internet and Web Services, Security in Mobile and Wireless Computing, साइबर सुरक्षा / Cyber Safety and Security, कंप्यूटर नेटवर्क / Computer Networks
  22. Paper 2 | Pedagogy: वृद्धि और विकास / Growth and Development, विकास के सिद्धांत / Theories of Development, Concept of Pedagogy, समावेशी शिक्षा / Inclusive Education, Experiential Pedagogy, आकलन और मूल्यांकन / Assessment and Evaluation, संज्ञानात्मक प्रक्रियाएँ / Cognitive Processes, समाजीकरण और जेंडर / Socialisation and Gender, National Education Policy (NEP) 2020
  23. Live Classes: RSSB Live Sessions
  24. Paper 1 - Full Mock Tests:
  25. Paper 2 - Full Mock Tests:
  26. BCI Previous Year Papers:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a structured lesson on the divisibility rules for integers, specifically focusing on 1, 2, 3, and 4. The instructor begins by defining the scope of integers to exclude fractions before introducing the trivial rule that any integer is divisible by 1. The lesson progresses systematically to more complex rules, starting with divisibility by 2, which relies on the parity of the last digit. Subsequently, the rule for divisibility by 3 is explained using the sum of digits method, including a demonstration on how to repeat the process for large numbers. Finally, the video covers divisibility by 4 through two methods: checking the last two digits and a mental math shortcut involving halving the number twice. Throughout the lecture, visual aids such as checkmarks, crosses, and step-by-step calculations are used to reinforce the concepts.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with an introduction to the concept of divisibility, specifically establishing that any integer is divisible by 1. The instructor emphasizes a critical definition on the slide: 'Any integer (not a fraction) is divisible by 1,' underlining key terms to ensure students distinguish between whole numbers and fractions. To illustrate this, the instructor lists specific examples of integers such as 8, 10, 729, and 499. Visual cues include checkmarks next to valid integers and crosses or exclusions for fractions, setting a foundational understanding of the number types applicable to these rules.

  2. 2:00 – 5:00 02:00-05:00

    The lesson transitions to the divisibility rule for 2, stating that a number is divisible by 2 if its last digit is even (0, 2, 4, 6, or 8). The instructor validates this rule using the examples '128 Yes' and '129 No,' clearly marking which numbers satisfy the condition based on their final digit. The segment also introduces a seven-digit number N represented as 'abcabc,' likely to set up future problems involving patterns. The teaching method involves underlining the rule and using visual checks to confirm whether specific numbers meet the criteria, reinforcing the concept of evenness.

  3. 5:00 – 10:00 05:00-10:00

    This section covers the divisibility rule for 3, explaining that a number is divisible by 3 if the sum of its digits is divisible by 3. The instructor demonstrates this with '381 (3+8+1=12, and 12÷3 = 4) Yes' and '217 (2+1+7=10, and 10÷3 = 3 1/3) No.' For larger numbers like '99996,' the rule is applied iteratively: summing digits to get 42, then summing again to get 6. The video then introduces the rule for 4, stating 'The last 2 digits are divisible by 4,' verified with examples like '1312 is (12÷4=3) Yes' and '7019 is not (19÷4=4 3/4) No.'

  4. 10:00 – 12:07 10:00-12:07

    The final segment reinforces the divisibility rule for 4 by introducing a 'quick check' method: halving the number twice to see if the result remains a whole number. The instructor demonstrates this with '12/2 = 6, 6/2 = 3' (Yes) and '30/2 = 15, 15/2 = 7.5' (No). The video concludes by applying these methods to a larger number, '1214,' and ends with a 'Thanks for watching' screen. The visual evidence includes handwritten calculations showing the division steps and explicit text confirming the rule that 'The last 2 digits are divisible by 4.'

The lecture follows a logical progression from simple to complex divisibility rules, ensuring students build confidence with each step. The instructor consistently uses visual verification methods like checkmarks and crosses to make abstract rules concrete. Key takeaways include the strict definition of integers for divisibility by 1, the reliance on the last digit for divisibility by 2 and 4, and the iterative summing of digits for divisibility by 3. The inclusion of a 'quick check' method for divisibility by 4 adds practical value, offering students an alternative mental math strategy. The use of specific numerical examples like 381 and 99996 ensures that students can apply the rules to both small and large numbers effectively.

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