Multiply 2-Digit Numbers in Just 5 Seconds

Duration: 4 min

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Inside: a video lesson and guided study material.

Module outline

  1. Quantitative Aptitude: Number System, Divisibility Rules, HCF LCM, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Mixture and Alligation, Partnership, Age Problems, Time and Work, Pipe and Cistern, Speed Time and Distance, Algebra, Arithmetic, Data Interpretation, Sequence and Series (Series), Logarithm, Powers and Exponents (Surds and Indices), Permutation and Combination, Probability, Speed Mathematics and Basic Mathematics, Trigonometry
  2. Logical Reasoning: Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Seating Arrangements, Puzzle Solving (Puzzles), Data Arrangement, Syllogisms, Inequality, Data Sufficiency, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Venn Diagram, Logical Sequence Of Words, Calendar, Clock, Cubes & Dices, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning)
  3. Verbal Ability: Noun, Pronoun, Adjectives, Verb, Adverb, Tenses, Subject Verb Agreement (Verb Noun Agreement), Articles, Preposition, Conjunction, Modals, Determiner, Vocabulary, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Active Passive Voice (Voice), Direct and Indirect Speech, Sentence Construction
  4. Data Structures (Domain Test): Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  5. Algorithms (Domain Test): Algorithm Analysis, Sorting Algorithms, Time Complexity Analysis, Greedy Algorithms
  6. OOPs (Domain Test): Object Oriented Programming (OOPS)
  7. DBMS (Domain Test): 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
  8. SQL (Domain Test): SQL
  9. Operating Systems (Domain Test): 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 (Domain Test): 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. Coding: Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir
  12. Written English Test: English Writing Ability
  13. Psychometric Test: Behavioral Assessment (Behavioral Competency Profiling) (Psychometric Test)
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.

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