## Glossary of GRE MATH FORMULAS - II

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- Factor or Divisor =
- Any integer that leaves no remainder (i.e a reaminder of 0) when it is dvided into another integer:1, 2, 5, 10 are the factors (or divisors) of 10

- Prime Number
- A positive integer that has exactly two divisors. The first few primes are 2, 3, 5, 7, 11, 13, 17 (not 1)

- bm bn

b raise to m, b raise to n = - bm

-- = (m -n)

bn b

- m n

(b )

= - mn

b

- 2

(squ a) = - sq a * sq a

- To compare two fractions
- convert them to decimals by dividing the numerator by the denominator

- To multiply two fractions,
- Multiply their numberator and multiply their denominators

3/5 * 4/7 = 3*4/5*7 = 12/35

- To divide any number by a fraction
- Multiply that number by the reciprocal of the fraction

3/5 divided by 2/3 = 3/5* 3/2 = 9/10

- To add or subtract fraction with different denominators, f
- first rewrite the fraction as equivalent fractions with the same denominator:

1/6+3/4 = 2/12 + 9/12 = 11/12

- Percent increase of qty =
- Actual increase

------------ * 100%

Original amount

- Percent decrease of qty =
- Atcual decrease

---------- * 100%

Original amount

- Ratio of 2 to 3 =
- 2/3 or 2:3

- Average of set of n numbers

= - Sum of the numbers

------------------

n

- Probability =
- Favorable Outcomes

-------------

Total Possible Outcomes

- Percent Formula

Part = - Percent * Whole

- The 3 exterior angles of a triangle add up to
- 360 degrees

- In any triangle, the sume of the measure os the three angles is
- 180 degrees

x+y+z = 180

- In any triangle

1) The longest side - = is the opposite the largest angle

- 2) the shortest side
- = is the opposite the smallest angle

- 3)Sides with the same length
- = Are opposite angles with the same measure

- In a 45-45-90 right triangle, the sides are =
- X, X, and X square 2

- In a 30-60-90 right triangles, the sides are =
- X, X Square 3 and 2X

- Area of Right trinagle =
- 1/2 * base * height

- Area of an equilateral triangle with equal sides =
- 2

S * Square 3

---------

4

- In any quadrilateral, the sume of the measures of the four angles
- = 360 degrees

- For Parallelogram

Area = - Base * Height

- Perimeter of Pallelogram =
- 2(a + b)

- Area of Rectangele =
- Length * Width

- Perimeter of Rectangel =
- 2(L + W)

- Area of a Square =
- 2

S

- Area of a square can also be =
- 1 2

- d

2

- Perimeter of a square =
- 4s (s = sides)

- Diameter of a circle =
- 2* radiuis

- Circumference of a Cirle =
- PI * D = 2 PI R

- Area of a circle =
- 2

PI r

- Length of an Arc
- (n/360) * (2PI r)

- Area of a sector, if n is the degree measure of the sector's central angle =
- 2)

(n/360) * (PI r

PI * R square

- Surface Area of Rectangular =
- 2(LW +LH + WH)= 2LW +LH +2 WH

- Suface Area of cube =
- 6e square

6 * e square

- Volume of a cylider =
- PI * R square * height

- Surface of a cylinder =
- 2PI r h

- Volume of a Rectangular solid =
- L * W * H

- Volume of a cube =
- 3

L * L * L = L

- Average speed =
- Total Distance

----------

Total time

- Average A per B =
- Total A

-----

Total B

- Probability formula

Probability = - Number of Favorable Outcome/

Total no. of Possible Outcomes

- If E is impossible, then P(E) =
- 0

- If it is certain that E will occur, then P(E)=
- 1

- In all other cases
- 0 <P(E)<1

- The probability that the even E will not occur =
- 1- P(E)

- Counting principle: if two jobs need tobe completed and there are m ways to do the first job and n ways to the second job, then there are
- m * n ways to do one job followed by th eother