Demo: Divisibility Rules of 5, 6 and 7

Duration: 12 min

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Inside: a video lesson and guided study material.

Module outline

  1. Quantitative Ability: Percentage, Profit and Loss, Ratio and Proportion (Ratios), Average, Time and Work, Speed Time and Distance, Simple Interest and Compound Interest, Age Problems, Number System, Divisibility Rules, HCF LCM, Algebra, Permutation and Combination, Probability, Data Interpretation, Logarithm, Sequence and Series (Series), Powers and Exponents (Surds and Indices), Speed Mathematics and Basic Mathematics
  2. Logical Reasoning: Seating Arrangements, Puzzle Solving (Puzzles), Data Arrangement, Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Data Sufficiency, Venn Diagram, Inequality, Series (Number and Letter Series) (Numerical Relations and Reasoning), Logical Sequence Of Words, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning)
  3. Verbal Ability: Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Subject Verb Agreement (Verb Noun Agreement), Tenses, Articles, Preposition, Conjunction, Modals, Active Passive Voice (Voice), Direct and Indirect Speech, Vocabulary, Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Sentence Completion (Fill in the blanks), Sentence Correction (Error Correction), Cloze Test (Cloze Passage), Facts, Inference and Judgements
  4. Programming Fundamentals (Technical): C Fundamentals
  5. Data Structures (Technical): Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  6. Algorithms (Technical): Algorithm Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Time Complexity Analysis, Advanced Algorithms
  7. OOPs (Technical): Object Oriented Programming (OOPS)
  8. DBMS (Technical): Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  9. SQL (Technical): SQL
  10. Operating Systems (Technical): Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  11. Computer Networks (Technical): Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, 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, Mobile Technology, Cloud Computing and IoT, Cyber and Info Security
  12. Software Engineering (Technical): Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  13. Coding/Automata Round: Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir, Pseudo Codes
  14. Personality / Behavioral Assessment: Behavioral Assessment (Behavioral Competency Profiling) (Psychometric Test)
  15. Writing Assessment: English Writing Ability
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a structured lesson on divisibility rules for the numbers 5, 6, and 7. The instructor begins by establishing the fundamental rule for divisibility by 5: a number is divisible if its last digit is either 0 or 5. This concept is reinforced through immediate examples, such as identifying 175 as divisible and 809 as not. The lesson then transitions to composite numbers, introducing a method where the divisor is broken down into factors (P = a x b) to simplify testing. The instructor demonstrates this with the number 6, requiring numbers to be both even and divisible by 3. The final section focuses on the number 7, presenting a specific arithmetic trick involving doubling the last digit and subtracting it from the remaining number to determine divisibility. The video concludes with a summary of these rules and examples verifying their application.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The lesson opens with the divisibility rule for 5, explicitly stating that a number is divisible if its last digit is 0 or 5. The instructor uses on-screen text to underline these key digits and provides immediate verification examples: 175 is marked 'Yes' because it ends in 5, while 809 is marked 'No'. The instructor then introduces the concept of composite numbers using fraction notation N/P and factorization P = a x b, setting up the framework for testing divisibility by products of factors.

  2. 2:00 – 5:00 02:00-05:00

    The instructor applies the composite number rule to demonstrate divisibility for products like 2x3=6 and 3x4=12. Specific examples are analyzed, such as breaking down the number 28 into factors 7 x 4. The focus shifts to the divisibility rule for 6, which requires a number to satisfy two conditions: it must be even and divisible by 3. The instructor verifies this with 114, showing the sum of digits (1+1+4=6) is divisible by 3, while 308 fails because the digit sum (11) is not divisible by 3.

  3. 5:00 – 10:00 05:00-10:00

    A specific trick for divisibility by 7 is introduced using the number 672. The method involves isolating the last digit (2), multiplying it by 5, and adding the result to the remaining number (67 + 10). The instructor then demonstrates a shortcut method where the last digit is doubled and subtracted from the rest. This process is applied to 672 (67 - 4 = 63, which is divisible by 7) and 105 (10 - 2 = 8, not divisible by 7), with visual annotations showing the arithmetic steps and final verification.

  4. 10:00 – 12:29 10:00-12:29

    The lesson concludes with a formal summary of the divisibility rule for 7, displayed as text: 'Double the last digit and subtract it from a number made by the other digits. The result must be divisible by 7.' The instructor tests this rule on 905, calculating 90 - (2*5) = 80, which is not divisible by 7. Examples of 672 and 105 are revisited to confirm their status as divisible or not. The video ends with a 'THANKS FOR WATCHING' screen, marking the completion of the instructional content.

The video systematically builds mathematical understanding by moving from simple single-digit rules to more complex composite and prime number strategies. The progression starts with the visual simplicity of checking the last digit for 5, then introduces logical conjunctions (AND conditions) for composite numbers like 6. The most complex concept, divisibility by 7, is taught through algorithmic tricks that transform the original number into a smaller, more manageable one. The instructor consistently uses visual cues like underlining, circling, and color-coded text to highlight critical steps in the calculation process. This pedagogical approach ensures that students can follow the logical flow from definition to application, reinforcing each rule with concrete numerical examples before moving to the next concept.

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