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Maths
6 Dec 2025
361
2 pages
Abi Thomson @abithomson_hose
Percentages help us calculate changes in value, whether it's depreciation (decrease) or appreciation (increase). This summary covers how... Show more
When an item loses value over time, we call it depreciation. To calculate the amount lost, multiply the original value by the depreciation percentage as a decimal. For example, with a car worth £9,550 that depreciates by 30%, we convert 30% to 0.3 and multiply 0.3 × £9,550 = £2,865 depreciation.
To find the new value after depreciation, you have two methods. You can subtract the depreciated amount from the original price £9,550 - £2,865 = £6,685. Alternatively, recognize that after a 30% decrease, the car is worth 70% of its original value, so calculate 0.7 × £9,550 = £6,685.
💡 Remember this shortcut If something decreases by X%, its new value is % of the original. For a 30% decrease, multiply by 0.7 to find the new value directly.
When property values increase, we call it appreciation. For a house bought for £87,500 that appreciates by 9% over time, we find the new value by multiplying the original amount by 1.09 (adding the percentage increase to 100%) £87,500 × 1.09 = £95,375.
Calculating depreciation follows similar logic. If a flat bought for £120,000 depreciates by 3% after two years, we find its new value by multiplying the original amount by 0.97 (100% - 3%) £120,000 × 0.97 = £116,400.
💡 Quick tip For increases, add the percentage to 100% (as a decimal). For a 9% increase, multiply by 1.09. For decreases, subtract the percentage from 100%. For a 3% decrease, multiply by 0.97.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
4
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore essential concepts of percentages, including calculations for simple and compound interest, percentage increase and decrease, and reverse percentages. This comprehensive guide provides step-by-step examples and practical applications to enhance your understanding and problem-solving skills. Ideal for students preparing for exams or seeking to improve their math proficiency.
MathsExplore essential techniques for calculating percentages, including percent increase, decrease, and reverse percentages. This study note covers practical applications such as compound interest and percentage change, providing clear examples and methods to enhance your understanding. Ideal for students looking to improve their math skills in real-world contexts.
MathsExplore essential concepts in fractions, decimals, and percentages with this comprehensive knowledge organizer. Learn to convert numbers to standard form, perform percentage calculations, and understand key definitions like denominators and mixed numbers. Ideal for Year 10 students preparing for exams.
MathsExplore essential techniques for calculating percentages with this detailed guide. Learn how to find percentages of amounts, including step-by-step examples for 10%, 15%, and 32%. Ideal for WJEC Intermediate tier students, this resource emphasizes practical applications and accuracy in financial contexts.
MathsExplore the different types of angles including acute, right, obtuse, straight, and reflex angles. This summary also covers adjacent, complementary, and supplementary angles, detailing their measurements and relationships in geometry.
MathsFoundation maths questions
MathsApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Abi Thomson
@abithomson_hose
Percentages help us calculate changes in value, whether it's depreciation (decrease) or appreciation (increase). This summary covers how to work out these changes step-by-step using simple multiplication methods.
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
When an item loses value over time, we call it depreciation. To calculate the amount lost, multiply the original value by the depreciation percentage as a decimal. For example, with a car worth £9,550 that depreciates by 30%, we convert 30% to 0.3 and multiply: 0.3 × £9,550 = £2,865 depreciation.
To find the new value after depreciation, you have two methods. You can subtract the depreciated amount from the original price: £9,550 - £2,865 = £6,685. Alternatively, recognize that after a 30% decrease, the car is worth 70% of its original value, so calculate: 0.7 × £9,550 = £6,685.
💡 Remember this shortcut: If something decreases by X%, its new value is % of the original. For a 30% decrease, multiply by 0.7 to find the new value directly.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
When property values increase, we call it appreciation. For a house bought for £87,500 that appreciates by 9% over time, we find the new value by multiplying the original amount by 1.09 (adding the percentage increase to 100%): £87,500 × 1.09 = £95,375.
Calculating depreciation follows similar logic. If a flat bought for £120,000 depreciates by 3% after two years, we find its new value by multiplying the original amount by 0.97 (100% - 3%): £120,000 × 0.97 = £116,400.
💡 Quick tip: For increases, add the percentage to 100% (as a decimal). For a 9% increase, multiply by 1.09. For decreases, subtract the percentage from 100%. For a 3% decrease, multiply by 0.97.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
4
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore essential concepts of percentages, including calculations for simple and compound interest, percentage increase and decrease, and reverse percentages. This comprehensive guide provides step-by-step examples and practical applications to enhance your understanding and problem-solving skills. Ideal for students preparing for exams or seeking to improve their math proficiency.
MathsExplore essential techniques for calculating percentages, including percent increase, decrease, and reverse percentages. This study note covers practical applications such as compound interest and percentage change, providing clear examples and methods to enhance your understanding. Ideal for students looking to improve their math skills in real-world contexts.
MathsExplore essential concepts in fractions, decimals, and percentages with this comprehensive knowledge organizer. Learn to convert numbers to standard form, perform percentage calculations, and understand key definitions like denominators and mixed numbers. Ideal for Year 10 students preparing for exams.
MathsExplore essential techniques for calculating percentages with this detailed guide. Learn how to find percentages of amounts, including step-by-step examples for 10%, 15%, and 32%. Ideal for WJEC Intermediate tier students, this resource emphasizes practical applications and accuracy in financial contexts.
MathsExplore the different types of angles including acute, right, obtuse, straight, and reflex angles. This summary also covers adjacent, complementary, and supplementary angles, detailing their measurements and relationships in geometry.
MathsFoundation maths questions
MathsApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
