Where I can find useful math for formulas, like the one used for finding overlapping information, and finding the total distance of a round trip? Unfortunately, none of my SAT books has these.
I usually just find them online as I need them and write them down in a notebook or on flashcards for later recall. I saw a list of them once, but many were repetitive and just getting them as I need them curtails it to my needs.
I have an article on this that gives all the important formulas with examples. Unfortunately most of the formulas are coded in html in the article. I will try to post parts of the article here tomorrow.
Total distance of round trip = distance of each way added together. Sounds obvious, but it's so simple that it's overlooked.
Di = RT (or dirt) Distance = rate x time.
Overlapping formula is silly. Sure, it works, but it's just another formula to remember (and often remember wrong if you mess up just one part, leading to the wrong answer). Instead, I recommend drawing out Venn diagrams. It's so much easier to see and not get wrong that way.
Below is an edited version of my article "The Math Formulas You Should Memorize for the SAT." It is edited to comply with CC rules, some images are missing, and others have been replaced with text:
I frequently get asked about the key formulas that students really need to know. After 12 years of tutoring SAT math, I have created a small list of the most important formulas that students should memorize. Everything you need to know on this subject is below.
(1) Let's begin with the formulas that are given to you in the beginning of each math section. Memorize these. Here they are.
(picture ommitted)
(2) The following simple formula will make it very easy for you to solve problems involving Percent Change.
Percent Change = Change/Original * 100
Note that this formula works both for problems involving percent increase and problems involving percent decrease.
Let's look at a simple example:
Suppose that x increases from 8 to 9. By what percent does x increase?
Well, the Original value is 8, and the Change is 9 - 8 = 1. Therefore we have
Replies to: SAT Math formulas
Di = RT (or dirt) Distance = rate x time.
Overlapping formula is silly. Sure, it works, but it's just another formula to remember (and often remember wrong if you mess up just one part, leading to the wrong answer). Instead, I recommend drawing out Venn diagrams. It's so much easier to see and not get wrong that way.
I frequently get asked about the key formulas that students really need to know. After 12 years of tutoring SAT math, I have created a small list of the most important formulas that students should memorize. Everything you need to know on this subject is below.
(1) Let's begin with the formulas that are given to you in the beginning of each math section. Memorize these. Here they are.
(picture ommitted)
(2) The following simple formula will make it very easy for you to solve problems involving Percent Change.
Percent Change = Change/Original * 100
Note that this formula works both for problems involving percent increase and problems involving percent decrease.
Let's look at a simple example:
Suppose that x increases from 8 to 9. By what percent does x increase?
Well, the Original value is 8, and the Change is 9 - 8 = 1. Therefore we have
Percent Change = 1/8