Math Tricks for INSTANT Calculation

tecmath
17 Oct 202309:02
EducationalLearning
32 Likes 10 Comments

TLDRIn this TechMath tutorial, viewers learn a quick method for multiplying by common numbers 5, 25, and 125. The process involves simple division followed by multiplication by a power of 10, making calculations instant and easy. The video explains the steps for each number, demonstrates with examples, and shows how to handle remainders. It encourages practice and ends with an invitation to support the channel.

Takeaways
  • 🔢 The video teaches a quick method for multiplying by the common numbers 5, 25, and 125.
  • 📝 To multiply by 5, divide the number by 2 and then multiply the result by 10.
  • 🔍 The reason this works is because 5 equals 10 divided by 2, so dividing and then multiplying by 10 is equivalent to multiplying by 5.
  • 🤔 For numbers that don't divide evenly by 2, use the remainder and add the corresponding multiple of 5 at the end.
  • 📈 To multiply by 25, divide the number by 4 and then multiply the result by 100, since 25 equals 100 divided by 4.
  • 📉 When multiplying by 25, if there is a remainder, multiply the remainder by 25 and add it to the result.
  • 🎯 For multiplying by 125, divide the number by 8 and then multiply by 1000, as 125 is 1000 divided by 8.
  • 🧩 In cases of remainders with 125, multiply the remainder by 125 and include it in the final result.
  • 📚 The method is demonstrated with various examples, including numbers with and without remainders.
  • 🚀 The video encourages practice with several sample problems to reinforce the learning of the multiplication technique.
  • 👍 The presenter asks viewers to like the video and leave comments, showing engagement with the audience.
Q & A

  • What is the main topic of the video?

    -The main topic of the video is a fast method for multiplying by common numbers such as 5, 25, and 125.

  • How does the method for multiplying by 5 work?

    -To multiply by 5, you divide the number by 2 and then multiply the result by 10.

  • Can you give an example of multiplying by 5 using the method described in the video?

    -Yes, for example, to multiply 34 by 5, you divide 34 by 2 to get 17, and then multiply 17 by 10 to get 170.

  • What is the reasoning behind the multiplication method for the number 5?

    -The method works because 5 is equal to 10 divided by 2, so dividing by 2 and then multiplying by 10 is the same as multiplying by 5.

  • How does the video handle cases where the number does not divide evenly by 2?

    -The video suggests using remainders and then adding the appropriate multiple of 5 to the result after multiplying by 10.

  • What is the method for multiplying by 25 as described in the video?

    -To multiply by 25, you divide the number by 4 and then multiply the result by 100.

  • Can you provide an example of multiplying by 25 using the video's method?

    -Sure, to multiply 36 by 25, you divide 36 by 4 to get 9, and then multiply 9 by 100 to get 900.

  • How does the video address remainders when multiplying by 25?

    -The video suggests dividing by 4 and then multiplying by 100, and if there is a remainder, multiplying the remainder by 25 and adding it to the result.

  • What is the method for multiplying by 125 as shown in the video?

    -To multiply by 125, you divide the number by 8 and then multiply the result by 1000.

  • Can you explain the process of multiplying by 125 with an example from the video?

    -Certainly, to multiply 48 by 125, you divide 48 by 8 to get 6, and then multiply 6 by 1000 to get 6000.

  • How does the video handle numbers that do not divide evenly by 8 when multiplying by 125?

    -The video recommends dividing by 8, multiplying by 1000, and then adding the appropriate multiple of 125 for any remainder.

Outlines
00:00
🔢 Quick Multiplication Tricks for 5, 25, and 125

This paragraph introduces a fast method for multiplying numbers by 5, 25, and 125. The presenter explains that multiplying by 5 can be achieved by dividing the number by 2 and then multiplying the result by 10. Examples are given, such as 34 * 5, which is calculated as (34 / 2) * 10 = 170. The method is justified by the fact that 5 is half of 10. The presenter also addresses how to handle remainders when dividing by 2, as demonstrated with 47 * 5, which is calculated as (47 / 2) * 10 + 5 = 235. The paragraph concludes with a teaser for the upcoming explanation of how to multiply by 25.

05:01
🚀 Mastering Multiplication by 25 and 125

The second paragraph delves into the multiplication methods for 25 and 125. It starts with the explanation for multiplying by 25, which is done by dividing the number by 4 and then multiplying by 100, as 25 equals 100 divided by 4. Examples include 36 * 25, calculated as (36 / 4) * 100 = 900, and 884 * 25, which is handled similarly. The presenter also demonstrates how to deal with remainders, as shown with 23 * 25, calculated as 3 * 25 + 20 * 4 + remainder, resulting in 575. The paragraph then transitions to multiplying by 125, which is 1000 divided by 8, and provides an example with 48 * 125, calculated as (48 / 8) * 1000 = 6000. The explanation includes handling remainders, as illustrated with 161 * 125, resulting in 20125 after considering the remainder. The paragraph ends with a prompt for the audience to try similar calculations with provided numbers and a call to action to support the TechMath channel.

Mindmap
Keywords
💡Multiplication
Multiplication is a mathematical operation where one number is added to itself a certain number of times. In the context of the video, it is the primary operation being taught for common numbers like 5, 25, and 125. The script demonstrates various methods to multiply by these numbers quickly, such as dividing by 2 and then multiplying by 10 for the number 5.
💡Common Numbers
Common numbers refer to frequently used or easily divisible numbers in mathematical operations. In this video, the focus is on the numbers 5, 25, and 125, which are chosen because they have simple relationships to base numbers like 10 and 100, making multiplication with them straightforward once the viewer understands the method.
💡Instant Calculation
Instant calculation implies the ability to compute results quickly without the need for traditional long multiplication methods. The video script teaches viewers how to achieve instant calculations by breaking down the multiplication process into simpler steps, such as dividing and then multiplying by powers of 10.
💡Division
Division is the process of splitting a number into equal parts. In the script, division is used as a preliminary step in the multiplication process. For example, to multiply by 5, the number is first divided by 2, and then the result is multiplied by 10 to achieve the final product.
💡Remainder
A remainder is what is left over after division when the divisor does not evenly divide the dividend. In the context of the video, when a number does not divide evenly by 2, 4, or 8, the remainder is used to adjust the final multiplication result. For instance, when multiplying 47 by 5, the remainder after dividing by 2 is added back into the calculation.
💡Powers of 10
Powers of 10 refer to the multiples of ten, such as 10, 100, and 1000. In the script, these are used as multipliers after division to simplify the multiplication process. For example, multiplying by 25 involves dividing by 4 and then multiplying the result by 100.
💡Techmath
Techmath appears to be the name of the channel or educational series that the video script is from. It likely focuses on teaching mathematical concepts and techniques, as evidenced by the script's focus on quick multiplication methods.
💡Like Button
The like button is a feature on many video platforms that allows viewers to express their approval or enjoyment of the content. In the script, the presenter encourages viewers to hit the like button if they find the multiplication techniques helpful.
💡Patron
A patron in the context of the video refers to a supporter of the Techmath channel, likely through a subscription or donation model. The script mentions becoming a patron as a way to support the channel, with a link provided in the description for interested viewers.
💡Comment
Comments are messages left by viewers on video platforms to share thoughts or feedback. The script invites viewers to leave a comment expressing their thoughts on the video, which can provide valuable feedback to the content creator.
Highlights

Introduction to a fast method for multiplying by common numbers 5, 25, and 125.

Step-by-step instruction on multiplying by 5 by dividing by 2 and then multiplying by 10.

Explanation of the mathematical rationale behind multiplying by 5 using division and multiplication.

Demonstration of multiplying 126 by 5 using the quick method.

Handling odd numbers in multiplication by 5 with remainders.

Introduction to multiplying by 25 using division by 4 and multiplication by 100.

Quick calculation of 36 multiplied by 25 with the new method.

Addressing more complex numbers like 884 when multiplying by 25.

Dealing with remainders in multiplication by 25 with the example of 23.

Transition to multiplying by 125, using division by 8 and multiplication by 1000.

Instant calculation of 48 multiplied by 125 using the quick method.

Example of multiplying 161 by 125, including handling remainders.

Practice exercises provided for the audience to apply the multiplication methods.

Solution to the practice exercise of multiplying 24 by 5.

Solution to the practice exercise of multiplying 33 by 5 with remainders.

Multiplication of 18 by 25 using the division and multiplication method.

Multiplication of 31 by 25, including handling remainders.

Final practice exercise of multiplying 138 by 125 with detailed steps.

Encouragement to like the video and support the TechMath channel.

Transcripts

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Mental MathMultiplicationQuick TricksEducationalMath SkillsNumber FactsLearning TipsInstant MathTechMathPatron Support