Concept of Reminders (Part 4)

Duration: 18 min

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Module outline

  1. Course Overview: About the Course
  2. Paper - 1 | Unit - 1 | Teaching Aptitude: Nature, Objectives & Characteristics of Teaching, Learners & Learning Process, Factors Affecting Teaching, Methods of Teaching, Teaching-Learning Aids & ICT Integration, Evaluation, Assessment & Measurement
  3. Paper - 1 | Unit - 2 | Research Aptitude: Introduction to Research, Validity & Reliability, Research Paradigms & Types of Research, Research Process Steps, Research Ethics, Writing & Publication
  4. Paper - 1 | Unit - 3 | Comprehension: Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions)
  5. Paper - 1 | Unit - 4 | Communication: Communication Basics, Language and Semiotics, Types of Communication, Communication Models, Mass Communication, Mass Media, Journalism, General Knowledge and General Studies related to Communication
  6. Paper - 1 | Unit - 5 | Mathematical Reasoning and Aptitude: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Number System, Percentage, Ratio and Proportion (Ratios), Simple Interest and Compound Interest, Speed Time and Distance, Powers and Exponents (Surds and Indices), Profit and Loss, Average, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Verbal Analogy (Word Based Analogy), Divisibility Rules, Calendar, Miscellaneous, Time and Work, Algebra
  7. Paper - 1 | Unit - 6 | Logical Reasoning: Syllogisms, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Venn Diagram, School Of Thoughts, Fallacy, Western Logic
  8. Paper - 1 | Unit - 7 | Data Interpretation: Data Interpretation
  9. Paper - 1 | Unit - 8 | Information and Communication Technology: MS Office Applications, Cyber Threats and Malware Attacks, Role of Internet and Web Services, Electronic Data Interchange and E-Commerce, Internet Fundamentals, Web Design & Development, Web Publishing & Hosting, Emerging Technologies, Terms & Abbreviations, Artificial Intelligence, Society, Law & Ethics, Keyboard Shortcuts, Website, Browser & Services
  10. Paper - 1 | Unit - 9 | People Development and Environment: Ecosystem, Biomes & Environmental Issues, MDG & SDG, Air Pollution, Water Pollution, Soil, Noise Pollution and Waste Management, Natural Resources, Energy & Disaster Management, Global Environmental Conventions – COP, Protocols & ISA
  11. Paper - 1 | Unit - 10 | Higher Education System: Vedic Education, Jainism & Buddhism, Ancient Universities, Pre-Independence Commissions, Post-Independence Policy, Higher Education Structure & Accreditation, Universities & Learning Programmes, Types of Education & NEP 2020
  12. Paper 2 | Unit 1 | Discrete Structures and Optimization: Propositional and Predicate Logic, Set Theory, Relations, Functions, Permutation and Combination, Probability, Graph Theory, Group Theory, Digital Systems & Boolean Basics, Boolean Expression, Boolean Minimization, Optimization
  13. Paper 2 | Unit 2 | Computer System Architecture: Logic Gates & Hardware, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep, Basics of COA, Register Transfer and Microoperations, Programming the Basic Computer, Instr Formats & Modes, Control Unit Design, Pipelining, Input Output Organisation, Cache Memory Organization, Multiprocessors
  14. Paper 2 | Unit 3 | Programming Languages and Computer Graphics: Language Design, C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, HTML Basics, XML, JavaScript-Basics, Java, Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing, OOPS with C++, Java Fundamentals
  15. Paper 2 | Unit 4 | Database Management Systems: 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, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  16. Paper 2 | Unit 5 | System Software and Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  17. Paper 2 | Unit 6 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  18. Paper 2 | Unit 7 | Data Structures and Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  19. Paper 2 | Unit 8 | Theory of Computation and Compilers: 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, 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
  20. Paper 2 | Unit 9 | Data Communication and Computer Networks: 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, Cloud Computing
  21. Paper 2 | Unit 10 | Artificial Intelligence: Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Fuzzy Sets, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms
  22. Live Classes: NTA UGC NET 2025 Live Class
  23. Paper 1 | Full Mock Tests:
  24. Paper 2 | Full Mock Tests:
  25. Paper 1 | Previous Year Papers:
  26. Paper 2 | Previous Year Papers:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video, presented by Yash Jain from Knowledge Gate, is a comprehensive tutorial on solving remainder problems in number systems, a common topic in competitive exams. The video begins with an introduction to the concept of remainders, using a simple division example (7 ÷ 2 = 3 R1) to establish the foundational idea. The main content consists of two complex problems. The first problem involves the sum of the reciprocals of the first 13 natural numbers, expressed as a fraction x/13!. The instructor demonstrates that to find the remainder when x is divided by 11, one must analyze the numerator of the sum after a common denominator is applied. The key insight is that for any term where the denominator is not divisible by 11, the corresponding numerator term will be divisible by 11, leaving only the term where the denominator is 11 as the only non-zero contributor to the remainder. The second problem asks for the remainder when N = (1! + 2! + 3! + ... + 1000!)^40 is divided by 10. The instructor explains that for n ≥ 5, n! is divisible by 10, so all terms from 5! onwards are 0 modulo 10. This simplifies the sum to (1! + 2! + 3! + 4!)^40 = (1 + 2 + 6 + 24)^40 = 33^40. The final step is to find the remainder of 33^40 when divided by 10, which is equivalent to finding the last digit of 33^40. The video concludes with a summary of the problem-solving techniques, emphasizing the use of modular arithmetic and the simplification of large expressions by identifying terms that become zero under the given modulus.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a title card for 'NUMBER SYSTEM' and then transitions to a presentation slide. The slide features the title 'NUMBER SYSTEM' and the tagline 'The mysterious world of numbers...'. The instructor, Yash Jain, is visible in a small window. He introduces the topic of the 'Concept of Remainders' and provides a simple example on the board: '7 ÷ 2 = 3 R1', with an arrow pointing to the '1' and labeling it 'Remainder'. This establishes the basic definition of a remainder as the leftover part of a division.

  2. 2:00 – 5:00 02:00-05:00

    The video presents the first problem: 'The expression sigma(1/n) from n=1 to 13 can also be written as x/13!. What would be the remainder if x is divided by 11?'. The instructor begins to solve this by writing the sum as 1/1 + 1/2 + 1/3 + ... + 1/13. He then multiplies the entire sum by 13! to get x, which results in the expression x = 13!/1 + 13!/2 + 13!/3 + ... + 13!/13. He explains that to find x mod 11, he needs to evaluate each term in the sum modulo 11.

  3. 5:00 – 10:00 05:00-10:00

    The instructor analyzes the terms of the sum x = 13!/1 + 13!/2 + ... + 13!/13 modulo 11. He explains that 13! is divisible by 11, so 13! ≡ 0 (mod 11). For any term where the denominator is not 11, the numerator 13! is divisible by 11, making the entire term 0 modulo 11. The only term that is not divisible by 11 is the one where the denominator is 11, which is 13!/11. He simplifies this term to 13 × 12 × 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 = 13 × 12 × 10!. He then states that the remainder is the value of 13 × 12 × 10! modulo 11, which he will calculate in the next step.

  4. 10:00 – 15:00 10:00-15:00

    The instructor calculates the remainder of 13 × 12 × 10! when divided by 11. He uses the property that (p-1)! ≡ -1 (mod p) for a prime p (Wilson's Theorem). Since 11 is prime, 10! ≡ -1 (mod 11). He then simplifies 13 × 12 modulo 11: 13 ≡ 2 (mod 11) and 12 ≡ 1 (mod 11). Therefore, the expression becomes 2 × 1 × (-1) = -2. Since the remainder must be positive, he adds 11 to get 9. The final answer for the first problem is 9. He then transitions to the second problem.

  5. 15:00 – 18:29 15:00-18:29

    The second problem is introduced: 'What is the remainder when N = (1! + 2! + 3! + ... + 1000!)^40 is divided by 10?'. The instructor explains that for n ≥ 5, n! is divisible by 10 (since it contains both 2 and 5 as factors), so n! ≡ 0 (mod 10). This means all terms from 5! to 1000! are 0 modulo 10. The sum simplifies to (1! + 2! + 3! + 4!)^40 = (1 + 2 + 6 + 24)^40 = 33^40. The problem now is to find 33^40 mod 10, which is the last digit of 33^40. He notes that the last digit of 33 is 3, so he needs to find the last digit of 3^40. He then calculates the pattern of the last digit of powers of 3: 3^1=3, 3^2=9, 3^3=7, 3^4=1, and the cycle repeats every 4. Since 40 is divisible by 4, the last digit is 1. The final answer is 1. The video ends with a 'Thank You for Watching' screen.

The video provides a clear and structured lesson on applying modular arithmetic to solve complex remainder problems. It begins with a fundamental concept and progresses to two distinct, challenging problems. The first problem demonstrates the power of simplification by identifying that only one term in a large sum contributes to the remainder when the modulus is a prime number, leveraging Wilson's Theorem. The second problem illustrates the technique of reducing a sum by recognizing that terms beyond a certain point become zero modulo the divisor. The core teaching method is the step-by-step breakdown of complex expressions into manageable parts, using properties of factorials and modular arithmetic to arrive at the solution. The progression from a simple example to two advanced problems effectively builds the viewer's problem-solving skills for competitive exams.

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