Demo: Divisibility Rules of 5, 6 and 7

Duration: 12 min

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Module outline

  1. General Intelligence & Reasoning: Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Logical Sequence Of Words, Syllogisms, Venn Diagram, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Data Sufficiency, Puzzle Solving (Puzzles), Data Arrangement, Cubes & Dices, Calendar, Clock, Arithmetic, Number System, Divisibility Rules, HCF LCM, Verbal Analogy (Word Based Analogy)
  2. General Awareness: Physics, Chemistry, Biology, History, Geography, Polity, Indian Economy, Environment, Static General Knowledge, GK- Current Affairs
  3. Engineering Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Linear Algebra, Calculus, Probability, Statistics
  4. Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep
  5. Computer Organisation & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design
  6. Programming & Data Structures: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  7. Databases: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control
  8. Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  9. Theory of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Complexity Theory
  10. Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment
  11. Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management
  12. Computer Networks: Introduction to CN, 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
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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