Multiply 2-Digit Numbers in Just 5 Seconds

Duration: 4 min

This video lesson is available to enrolled students.

Return to /learn/RSSB-SENIOR-COMPUTER-INSTRUCTOR/paper-1-basic-numeracy/speed-mathematics-and-basic-mathematics/speed-maths/asset-multiply-2-digit-numbers-in-just-5-seconds after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About the Course: About the Course
  2. Paper-1 & 2 | Basic Numeracy: Ratio and Proportion (Ratios), Divisibility Rules, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Percentage, Average, Mensuration and Geometry, Age Problems, Arithmetic, Statistics, Probability, Profit and Loss, Simple Interest and Compound Interest, Partnership, Speed Mathematics and Basic Mathematics, Algebra, Powers and Exponents (Surds and Indices), Time and Work, Pipe and Cistern, RSSB Specific Videos - Basic Numeracy
  3. Paper-1 & 2 | Data Interpretation: Data Interpretation
  4. Paper-1 & 2 | General Mental Ability: Mental Ability, RSSB Specific Videos - Mental Ability
  5. Paper-1 & 2 | Logical Reasoning and Analytical Ability: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Syllogisms, Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Venn Diagram, Analogy, Ranking, Order and Sequence, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Data Arrangement, Logical Sequence Of Words, Crypt Arithmetic
  6. Paper-1 & 2 | Decision Making and Problem Solving: Selection Decision Table (Decision Making)
  7. Paper-1 | General Science: Physics, Biology, Chemistry, RSSB Specific Videos
  8. Paper-1 | General Awareness: State Wise GK, GK- Current Affairs
  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, Artificial Intelligence
  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: Child Development, Concept of Pedagogy, Psychology, Theories, Inclusive Education, Experiential Pedagogy, Curriculum Framework & Reforms, National Education Policy (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 presents a series of mental math techniques for multiplying two-digit numbers, focusing on a method that simplifies calculations by breaking them into parts. The instructor, Yash Jain Sir, demonstrates the method on several examples, including 21 x 22, 41 x 53, 23 x 92, 95 x 43, and 56 x 78. The core technique involves multiplying the tens digits, multiplying the units digits, and then adding the cross-products of the tens and units digits. The video uses a digital whiteboard to show the step-by-step process, with the instructor explaining the logic behind each calculation. The presentation is structured as a tutorial, with a clear progression from one example to the next, and concludes with a 'Thanks for Watching' screen.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a title card for 'SPEED MATHS' and then transitions to the instructor, Yash Jain Sir, who introduces the first problem: 21 x 22. He begins the calculation by writing the multiplication on the digital whiteboard. He multiplies the units digits (1 x 2) to get 2, which becomes the last digit of the answer. He then multiplies the tens digits (2 x 2) to get 4, which becomes the first digit of the answer. The middle digit is found by adding the cross-products (2 x 2 + 1 x 2 = 4 + 2 = 6). The final answer, 462, is written below the problem. The instructor explains this process as a method for quick mental calculation.

  2. 2:00 – 4:22 02:00-04:22

    The instructor proceeds to the next example, 41 x 53. He applies the same method: multiplying the units digits (1 x 3 = 3), the tens digits (4 x 5 = 20), and the cross-products (4 x 3 + 1 x 5 = 12 + 5 = 17). He then combines these results, carrying over the tens digit from 20 and 17 to get the final answer, 2173. He repeats this process for 23 x 92, 95 x 43, and 56 x 78, demonstrating the method's consistency. For 95 x 43, he shows that 5 x 3 = 15, so he writes 5 and carries 1. The cross-products are 9 x 3 + 5 x 4 = 27 + 20 = 47, plus the carried 1 makes 48. The tens digits give 9 x 4 = 36, plus the carried 4 from 48 makes 40. The final answer is 4085. The video concludes with a 'Thanks for Watching' screen.

The video is a structured tutorial on a specific mental math shortcut for multiplying two-digit numbers. The central idea is to decompose the multiplication into three parts: the product of the tens digits, the product of the units digits, and the sum of the cross-products. The instructor demonstrates this method on five different problems, showing how to handle carrying over digits when the intermediate results are two-digit numbers. The progression from simple to more complex examples (e.g., 21x22 to 95x43) illustrates the method's versatility and reinforces the learning. The consistent use of a digital whiteboard for step-by-step calculations makes the process clear and easy to follow.

Loading lesson…