GRE Math

Question 1

Percentage Change Formula

Answer 1

(Difference/Original) X 100

Question 2

Standard Deviation Percents

Answer 2

From the center, 1 SD = 34% or 68%, 2 SD = 14% or 96%

Question 3

Third Side Rule

Answer 3

The length of any one side of a triangle must be less than the sum of the other two sides and greater than the difference between the other two sides

Question 4

Height of an equilateral triangle

Answer 4

Xsqrt(3) where X = half of the base

Question 5

Hypotenuse of a right isosceles (diagonal of a square)

Answer 5

Xsqrt(2) where X = the length of the other sides

Question 6

Diagonal in a three dimensional box

Answer 6

A^2+B^2+C^2=D^2

Question 7

A is X% of B

Answer 7

A = XB/100

Question 8

Even+Even

Answer 8

Even

Question 9

Odd+Odd

Answer 9

Even

Question 10

Even+Odd

Answer 10

Odd

Question 11

Even X Even

Answer 11

Even

Question 12

Odd X Odd

Answer 12

Odd

Question 13

Even X Odd

Answer 13

Even

Question 14

Prime Numbers

Answer 14

2, 3, 5, 7, 11, 13, 17, 19, 23, 29 (no negative primes)

Question 15

Divisible by 3

Answer 15

Its digits add up to a multiple of 3

Question 16

Divisible by 4

Answer 16

Its last two digits are divisible by 4

Question 17

To divide fractions

Answer 17

Flip and multiply

Question 18

Total interior angles of a polygon

Answer 18

(n-2)180, n = number of sides

Question 19

Common Quadratic pattern

Answer 19

X^2 + 2XY + Y^2

Question 20

Height of a triangle

Answer 20

Perpendicular to the base from the opposite vortex.