So you want to take the SAT? This is quite the challenge for nonnative English speakers as it’s even a challenge for native speakers! Luckily, half the test is given in the universal language… MATH. Even so, I’ve noticed some of the math is taught differently in US schools and some of the questions seem to be more focused on this style of problem. I am talking about percentages specifically. I have seen many students struggle with percentages and they almost always make the same mistakes. I’m hoping the strategy that I lay out below will simplify the problems and help you solve them more quickly, but with most maths there are many different ways to approach the same problem. Some approaches will be easier for some students and the same approach will be more difficult for others. This is the technique with which I’ve had the most success.
Part 1: Increasing by a percentage
Ex: What is 180 increased by 5%?
The quickest way to solve this is to write this 180 * 1.05 = 189.
Hold up.
Why is there a 1.05?
I took a shortcut! 180 increased by 5% can be written as:
180 + 180 * 0.5 which is rewritten 180 * (1+0.5) which simplified is 180 * 1.05
I am using the distributive property of multiplication to get 180 * (1+0.5). An easy way to think of this without the steps is to use this formula when increasing Y by percentage X.
Y*(1+X)
Side note: My thought process for solving this on the exam would go something like this. “180 increased by 5%. Do I know 5% of 180? No. What is 10% of 180? Move the decimal to the left so 18, and 5% is half of 10% so 5% must be 9. 180 plus 9 is 189.”
Part 2: Decreasing by a percentage
Ex: What is 120 decreased by 10%?
The quickest way for solving this would be 120 * 0.9 = 108.
Wait.
Stop.
Where did 0.9 come from?
I took a shortcut again. 120 decreased by 10% can be written as:
120 – 120 * 0.1 which is rewritten 120 * (10.1) which is equal to 120 * 0.9
In short, if you have a value Y and are decreasing by percentage X use this formula:
Y*(1X)
Side note: If you are doing this math in your head, which is necessary for the “no calculator” portion, this is my thought process. “What is 10 percent of 120? Just move the decimal point to the left so 12. Okay, so 120 minus 12 is 108.”
SAT Math  Percents
Quizsummary
0 of 10 questions completed
Questions:
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
Information
Practice: Solve these problems using the technique I described above. Try my thought process as well and see if it helps!
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
0 of 10 questions answered correctly
Your time:
Time has elapsed
You have reached 0 of 0 points, (0)
Categories
 Not categorized 0%

Nice work! Did you get the result you were expecting? If not, feel free to take the quiz a second time!
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 Answered
 Review

Question 1 of 10
1. Question
Increase 40 by 60%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 2 of 10
2. Question
Decrease 60 by 5%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 3 of 10
3. Question
Increase 200 by 15%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 4 of 10
4. Question
Decrease 360 by 17.5%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 5 of 10
5. Question
Increase 25 by 20%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 6 of 10
6. Question
Decrease 240 by 7.5%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 7 of 10
7. Question
Increase 100 by 4%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 8 of 10
8. Question
Increase 10 by 4%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 9 of 10
9. Question
Decrease 20 by 4%
Correct
Well done!
Incorrect
Not quite, better luck next time!

Question 10 of 10
10. Question
Decrease 10 by 50%
Correct
Well done!
Incorrect
Not quite, better luck next time!
We hope that satisfied your hunger for learning! If you’re looking for a little more for dessert, here’s the rest of our menu: https://scrambledeggsinglese.it/englishexercises/. Happy with your service? Give us a like on Instagram or swing by our English school in Milan for an English feast!