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 / आधारभूत संख्यात्मक योग्यता: Ratio and Proportion / अनुपात और समानुपात, Divisibility Rules / विभाज्यता के नियम, Mixture and Alligation / मिश्रण और एलिगेशन, Permutation and Combination / क्रमचय और संचय, Logarithm / लघुगणक, Number System / संख्या पद्धति, HCF and LCM / महत्तम समापवर्तक और लघुत्तम समापवर्त्य, Sequences, Series and Combinatorics / अनुक्रम, श्रेणी और संयोजन, Time, Speed and Distance / समय, चाल और दूरी, Percentage / प्रतिशत, Average / औसत, Solid Mensuration / घन क्षेत्रमिति, Age Problems / आयु संबंधी प्रश्न, Arithmetic / अंकगणित, Statistics / सांख्यिकी, Probability / प्रायिकता, Profit, Loss and Discount / लाभ, हानि और बट्टा, Simple and Compound Interest / साधारण और चक्रवृद्धि ब्याज, Partnership / साझेदारी, Speed Mathematics and Basic Mathematics / द्रुत गणित और आधारभूत गणित, Algebra / बीजगणित, Simplification, Indices and Surds / सरलीकरण, घातांक और करणी, Time and Work / समय और कार्य, Pipe and Cistern / नल और टंकी, RSSB Specific Videos - Basic Numeracy / RSSB विशेष वीडियो - आधारभूत संख्यात्मक योग्यता, Sets, Relations, Functions and Discrete Mathematics / समुच्चय, संबंध, फलन और विविक्त गणित, Number Systems and Number Theory / संख्या पद्धति और संख्या सिद्धांत, Coordinate Geometry, Vectors and 3D Geometry / निर्देशांक ज्यामिति, सदिश और त्रिविमीय ज्यामिति, Polynomials, Equations and Complex Numbers / बहुपद, समीकरण और सम्मिश्र संख्याएँ
  3. Paper-1 & 2 | Data Interpretation / आँकड़ों की व्याख्या: Data Interpretation / आँकड़ा निर्वचन
  4. Paper-1 & 2 | General Mental Ability / सामान्य मानसिक योग्यता: Mental Ability / मानसिक योग्यता, RSSB Specific Videos - Mental Ability / RSSB विशेष वीडियो - मानसिक योग्यता
  5. Paper-1 & 2 | Logical Reasoning and Analytical Ability / तार्किक तर्कणा एवं विश्लेषणात्मक क्षमता: Series / श्रेणी, Coding-Decoding / कूट लेखन एवं कूट वाचन, Data Sufficiency / आँकड़ों की पर्याप्तता, Non-Verbal Reasoning / अशाब्दिक तर्क, Syllogisms / न्यायवाक्य, Seating Arrangement and Puzzles / बैठक व्यवस्था एवं पहेलियाँ, Blood Relations / रक्त संबंध, Direction and Distance / दिशा एवं दूरी, Analytical Reasoning (Counting Figures Reasoning) / विश्लेषणात्मक तर्क (आकृति गणना तर्क), Mathematical Operations and Missing Numbers / गणितीय संक्रियाएँ एवं लुप्त संख्या, Calendar and Clock / कैलेंडर एवं घड़ी, Clock / घड़ी, Cubes, Dice and Figure Counting / घन, पासा एवं आकृतियों की गिनती, Venn Diagrams, Syllogism and Inequalities / वेन आरेख, न्याय वाक्य एवं असमानता, Analogy and Classification / सादृश्यता एवं वर्गीकरण, Order and Ranking / क्रम एवं रैंकिंग, Statement-Based Reasoning / कथन आधारित तार्किक विवेचन, Data Arrangement / आँकड़ों की व्यवस्था, Alphabet and Number Test / वर्णमाला एवं संख्या परीक्षण, Crypt Arithmetic / कूट अंकगणित
  6. Paper-1 & 2 | Decision Making and Problem Solving / निर्णय लेना एवं समस्या समाधान: Data Sufficiency and Decision Making / आँकड़ों की पर्याप्तता एवं निर्णय क्षमता
  7. Paper-1 | General Science / सामान्य विज्ञान: Scientific Achievements and Research / वैज्ञानिक उपलब्धियाँ और अनुसंधान, Biology / जीव विज्ञान, Chemistry / रसायन विज्ञान, RSSB Specific Videos / RSSB विशेष वीडियो
  8. Paper-1 | General Awareness / सामान्य जागरूकता: State-Specific General Knowledge / राज्य विशेष सामान्य ज्ञान, Current Affairs / समसामयिकी
  9. Paper-2 | Fundamentals of Computer: Basics of COA, Number System, Floating Point Rep, Number Representation
  10. Paper - 2 | Digital Logic Systems: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits
  11. Paper-2 | Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Linux OS, Distributed Systems
  12. Paper-2 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Relational Calculus, File Organization & Indexing, Transaction Management, Concurrency Control
  13. Paper-2 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. Paper-2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  15. Paper 2 | Oops, C++, Java: Language Design, OOPS with C++, Java, .Net Programming, Java Fundamentals
  16. 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
  17. Paper 2 | Emerging Trends and AI: Emerging Tech Trends, Computer Fundamentals, Trade, Marketing and Consumer Protection / व्यापार, विपणन एवं उपभोक्ता संरक्षण, Computer Networks, Internet of Things, Cloud Computing
  18. Paper-2 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Advanced Algorithms
  19. Paper 2 | Data Communication and Network Security: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security, Ethical Hacking
  20. Paper-2 I Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  21. Paper-2 | Computer Organization and Architecture: Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations
  22. Paper-2 | Web Development: JavaScript-Basics, HTML Basics, CSS, XML
  23. Pedagogy / शिक्षाशास्त्र: Growth and Development / वृद्धि और विकास, Concept of Pedagogy / शिक्षाशास्त्र की संकल्पना, Cognitive Processes / संज्ञानात्मक प्रक्रियाएँ, Theories of Development / विकास के सिद्धांत, Inclusive Education / समावेशी शिक्षा, Experiential Pedagogy / अनुभवात्मक शिक्षाशास्त्र, Socialisation and Gender / समाजीकरण और जेंडर, National Education Policy (NEP) 2020 / राष्ट्रीय शिक्षा नीति (NEP) 2020
  24. Live Sessions: RSSB Live Sessions
  25. RSSB Paper 1 - Full Mock Tests:
  26. RSSB Paper 2 - Full Mock Tests:
  27. SCI 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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