Percentage Math Trick 2 - Solve percentages mentally - percentages made easy!
TLDRThis Tech Math video introduces a mental math technique for calculating percentages of a given number. The host explains the concept of percentages and demonstrates how to quickly determine 50%, 10%, 5%, and 1% of a number by moving the decimal point. The method simplifies complex percentages by breaking them into these basic fractions and mentally adding or subtracting the results. The video includes several examples, encouraging viewers to practice both mentally and on paper to master the skill.
Takeaways
- 📚 The video provides a mental method for calculating percentages of a given amount.
- ⏱ The audience is given 5 seconds to answer the example question: 12% of 80, which equals 9.6.
- 🔢 Understanding the concept of 'percent' as a number out of 100 is crucial for mental calculations.
- 💯 100% of a number is simply the number itself.
- 🍞 50% of a number is half of the number.
- 🔟 10% of a number is found by dividing the number by 10, moving the decimal place one position to the left.
- 📉 5% of a number is calculated by moving the decimal place two positions to the left and then halving the result.
- 📈 1% of a number is found by moving the decimal place two positions to the left.
- 📌 The method involves breaking down percentages into parts of 10% and 1% for easier mental calculation.
- 🧠 Practice is recommended, starting with writing out calculations and then transitioning to mental math.
- 📝 The video concludes with a suggestion to practice these methods and verify answers with a calculator if needed.
Q & A
What is the main topic of the video?
-The main topic of the video is a method for mentally calculating percentages of a number.
What is the first example given in the video to demonstrate the method?
-The first example is calculating 12% of 80, which should be answered within 5 seconds.
What is the significance of understanding what a percentage means according to the video?
-Understanding that a percentage means 'out of 100' is crucial for mentally calculating percentages, as it helps in breaking down the problem into parts of 100.
How is 100% of a number calculated in the video?
-100% of a number is the number itself, as it represents the whole.
What is the method for calculating 50% of a number as shown in the video?
-50% of a number is half of the number, which is calculated by dividing the number by 2.
How does the video suggest calculating 10% of a number?
-The video suggests moving the decimal place one position to the left to calculate 10% of a number.
What is the approach for calculating 5% of a number as described in the video?
-5% of a number is calculated by considering it as half of 10%, which involves moving the decimal place one position to the left and then dividing by 2.
How is 1% of a number calculated according to the video?
-1% of a number is calculated by dividing the number by 100, which involves moving the decimal place two positions to the left.
What is the method for mentally calculating 12% of a number as explained in the video?
-12% can be thought of as 1 * 10% plus 2 * 1%. First, calculate 10% of the number, then calculate 2 * 1% of the number, and add the two results together.
What is the final recommendation given by the video for practicing these mental calculations?
-The video recommends writing out calculations initially to understand the method, then practicing mentally, and using a calculator to check answers for accuracy.
Outlines
📚 Introduction to Mental Percentage Calculation
The video begins with an introduction to the concept of mental percentage calculation. The host explains the meaning of 'percent' and emphasizes its relation to the number 100. The audience is challenged to calculate 12% of 80 within 5 seconds, with the correct answer being 9.6. The host then promises to demonstrate a method for quickly calculating percentages mentally, starting with understanding key percentages like 100%, 50%, 10%, 5%, and 1%, and how they relate to the whole number.
🔢 Understanding Basic Percentage Calculations
This paragraph delves into the specifics of calculating basic percentages. It explains that 100% of a number is the number itself, 50% is half of the number, and 10% is one-tenth, which can be calculated by moving the decimal place one position to the left. For 5%, the method involves dividing by 10, and for 1%, the decimal place is moved two positions to the left. The host illustrates these concepts with examples and encourages the audience to practice these mental calculations.
🧠 Applying the Method to Calculate Complex Percentages
The host guides the audience through applying the mental calculation method to more complex percentages, such as 12%, 51%, and 98% of various numbers. The method involves breaking down the percentage into simpler parts like 10% and 1%, and then mentally adding or subtracting these parts to find the answer. The host provides examples, such as calculating 51% of 70 and 98% of 680, and encourages the audience to try these calculations both mentally and on paper to reinforce their understanding.
📝 Practice and Mastery of Mental Percentage Calculation
The final paragraph focuses on practicing the mental calculation method with more examples, including calculating 21% of 60, 42% of 45, and 56% of 440. The host demonstrates the thought process for these calculations, emphasizing the importance of breaking down the percentages into their component parts and mentally combining them to find the final result. The video concludes with encouragement for the audience to continue practicing and to use a calculator to check their answers as they become more comfortable with the method.
Mindmap
Keywords
💡Percentage
💡Mental Calculation
💡Key Percentages
💡Decimal Place
💡Halving
💡Dividing by Ten
💡Complex Percentages
💡Mental Math Techniques
💡Practice
💡Calculator
Highlights
Introduction to a method for mentally calculating percentages of a number.
Understanding the concept of 'percent' as parts out of 100.
Simplification of 100% of a number as the number itself.
Calculating 50% of a number as half of the number.
Method for calculating 10% of a number by dividing by 10.
Approach to calculating 5% of a number by dividing by 20.
Technique for finding 1% of a number by dividing by 100 and moving the decimal place twice.
Combining percentages mentally for complex calculations, such as 12%.
Example calculation of 12% of 80 resulting in 9.6.
Suggestion to practice writing out calculations before moving to mental math.
Challenge to calculate 51% of 70 and the method to arrive at the answer of 35.7.
Explanation of calculating 98% of 680 with a step-by-step breakdown.
Providing a series of percentage calculation challenges for the viewer.
Detailed walkthrough of calculating 21% of 60 resulting in 12.6.
Complex calculation of 42% of 45 leading to the answer of 18.9.
Advanced example of calculating 56% of 440 with a final answer of 246.4.
Recommendation to verify calculations with a calculator when starting out.
Closing remarks encouraging practice and summarizing the mental math method's benefits.
Transcripts
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