25 GRE Math Formulas You Absolutely Need to Know
The Quantitative section of the GRE doesn't really have many complicated math concepts. Try to memorize as many of the math tricks below to make your GRE Quantitative section a breeze!
25 GRE Math Formulas
1. 3:4:5 Triangle is a "Pythagorean triple" with a 90° angle and sides lengths of 3:4:5 or 6:8:10 or 12:16:20 . . .
2. 30°-60°-90° triangle has sides of lengths of s - s√3 - 2s.
3. 45°-90°-45° triangle has sides of lengths s - s√2 - s.
4. (n-2 =180) = The sum of all interior angles of any polygon
5. a²+b²=c² = the Pythagorean Theorem
6. 1/2(base * height) = area of a triangle
7. side² = area of a square
8. length*width = area of a rectangle
9. 1/2(base1 + base2) * height = area of a trapezoid
10. base*height = area of a parallelogram
11. C=2Î r = circumference of a circle
12. Î r² = area of a circle
13. Î r³ = volume of a circle
14. length * width *height = volume of rectangular solid
15. edge³ = Volume
16. (1/3)³ = (1³/3³) = 1/27
17. Distance between two points = √[(X2-X1)²+(Y2-Y1)²
18. Standard deviation: the greater the standard deviation, the more spread out a set of values is. The small the standard deviation, the more closely the values are to the mode.
19. Fraction tip: 1/y + 1/x = x + y /xy. Example: 1/2 +1/3 = 2 +3 / 3 * 2 = 5/6
20. Simple interest = P[(1 + rt)/100], where P= Principal, r=rate, and t=time. So the interest on $100 at 5% for two years = 100[(1 + .05*2)/100] = $11
21. Compound interest = P[(1 + r/100n]^nt, where P= Principal, r=rate, n=number of periods, and t=time. So the compound interest on $100 at 5% for two years, compounded monthly = 100[(1 + .05/100*12]^12*2 = $110.49
22. Work rate formula = (1/time taken by both) = (1/time taken by person A) + (1/ time taken by person B)
23. Distance = rate * time
24. Order of operations = PEMDAS = Parentheses, Exponents, Multiplication, Division, Addition, Subratction
25. Solving an inequality: when multiplying both sides by a negative number, always switch the direction of the inequality sign. So -2x > 6 yields x
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