Multiply 2-Digit Numbers in Just 5 Seconds
Duration: 4 min
This video lesson is available to enrolled students.
Inside: a video lesson and guided study material.
Module outline
- Mathematics: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Percentage, Average, Powers and Exponents (Surds and Indices), Algebra, Probability, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Mental Ability, Age Problems, Partnership, Statistics, Arithmetic, Speed Mathematics and Basic Mathematics
- General Intelligence & Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Crypt Arithmetic, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence, Clerical Aptitude, Verbal Classification
- General Awareness: Polity, Evolution of Indian Banking (Banking & Financial Awareness), Physics, Biology, Chemistry, History, Geography, Indian Economy, Static General Knowledge, GK- Current Affairs, NEP 2020, Environment
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
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.
2:00 – 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.