Divisibility Rules of 28, 29, 30 and 31

Duration: 10 min

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Inside: a video lesson and guided study material.

Module outline

  1. Quantitative Aptitude: Number System, Percentage, Profit and Loss, Ratio and Proportion (Ratios), Average, Time and Work, Speed Time and Distance, Simple Interest and Compound Interest, Mixture and Alligation, Data Interpretation, Permutation and Combination, Probability, Logarithm, Powers and Exponents (Surds and Indices), Age Problems, Divisibility Rules, Partnership, HCF LCM, Algebra, Pipe and Cistern
  2. Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Analogy, Coding Decoding, Blood Relations, Directions (Direction Test), Syllogisms, Logical Sequence Of Words, Data Sufficiency, Seating Arrangements, Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Data Arrangement
  3. English Language: Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Vocabulary, Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Active Passive Voice (Voice), Direct and Indirect Speech, Cloze Test (Cloze Passage), Tenses, Subject Verb Agreement (Verb Noun Agreement), Preposition, Articles, Conjunction, Adverb
  4. Written English Test: English Writing Ability
  5. Coding: Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir
  6. Communication Round: Communication Assessment
  7. DBMS (Technical Interview): 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, Big Data Systems, NoSQL, Data Warehousing & Mining
  8. SQL (Technical Interview): SQL
  9. Operating Systems (Technical Interview): 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
  10. Computer Networks (Technical Interview): 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
  11. OOPs (Technical Interview): Object Oriented Programming (OOPS)
  12. HR Interview: MR & HR Interview Preparation
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video presents a series of divisibility rules for the numbers 28, 29, 30, and 31, taught by an instructor named Yash Jain Sir. The video begins with a title card and a colorful, hand-drawn diagram illustrating various divisibility rules. The main content consists of four distinct slides, each dedicated to a specific number. For 28, the rule is that a number is divisible by 28 if it is divisible by both 4 and 7, with the example of 140 being used. For 29, the rule is to add three times the last digit to the remaining leading truncated number, and if the result is divisible by 29, then so is the original number, demonstrated with the example 15689. For 30, the rule is that a number must be divisible by both 3 and 10, illustrated with the example 270. Finally, for 31, the rule is to subtract three times the last digit from the remaining leading truncated number, with the example 7998 being shown. The video concludes with a 'Thanks for Watching' screen.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a title card displaying 'DIVISIBILITY RULES' over a background of scattered numbers. This transitions to a colorful, hand-drawn diagram titled 'DIVISIBILITY RULES' which visually explains rules for numbers 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11. The instructor, Yash Jain Sir, appears in a small window in the bottom right corner. The first main slide is then shown, titled 'Divisibility Rule of 28'. It states that a number is divisible by 28 if it is divisible by 4 and by 7, with the example 140. The instructor begins to explain the rule, and the number 28 is written as 4 x 7 on the slide.

  2. 2:00 – 5:00 02:00-05:00

    The video continues to focus on the 'Divisibility Rule of 28'. The instructor explains that since 28 = 4 x 7, a number must be divisible by both 4 and 7. He demonstrates this with the example 140. He shows that 140 divided by 4 is 35, and 140 divided by 7 is 20. He also writes the multiplication 28 x 5 = 140 to reinforce the concept. The slide remains on screen, and the instructor's voiceover explains the logic behind the rule, emphasizing that if a number is divisible by two co-prime numbers, it is divisible by their product.

  3. 5:00 – 10:00 05:00-10:00

    The video transitions to a new slide titled 'Test for divisibility by 29'. The rule is stated: 'Add three times the last digit to the remaining leading truncated number. If the result is divisible by 29, then so was the first number.' An example is provided: 15689. The instructor demonstrates the process step-by-step: 1568 + 3*9 = 1568 + 27 = 1595. He continues: 159 + 3*5 = 159 + 15 = 174. Then: 17 + 3*4 = 17 + 12 = 29. Since 29 is divisible by 29, the original number 15689 is also divisible by 29. The video then moves to the 'Divisibility Rule of 30', stating it is divisible by 3 and 10, with the example 270. Finally, it presents the 'Test for divisibility by 31', which is to 'Subtract three times the last digit from the remaining leading truncated number.' The example 7998 is used: 799 - 3*8 = 799 - 24 = 775. Then: 77 - 3*5 = 77 - 15 = 62. Since 62 is 2*31, 7998 is divisible by 31.

  4. 10:00 – 10:05 10:00-10:05

    The video concludes with a final screen. The background is a dark purple gradient. In the center, the text 'THANKS FOR WATCHING' is displayed in a large, white, sans-serif font. This is the end of the lecture.

The video provides a clear and structured lesson on advanced divisibility rules. It follows a consistent pattern: introducing a rule for a specific number, explaining the logic (often by breaking the number into its prime factors), and then demonstrating the rule with a detailed, step-by-step example. The use of a hand-drawn diagram at the beginning provides context, while the subsequent slides focus on one rule at a time, ensuring clarity. The progression from 28 to 31 is logical, covering a range of composite numbers and demonstrating different types of rules (multiplication, addition, subtraction). The instructor's methodical approach makes the concepts accessible for students preparing for competitive exams.

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