GRE math
Home > Flashcards > Print Preview
The flashcards below were created by user
cfalgo1
on
FreezingBlue Flashcards. What would you like to do?

the angles in a triangle sum up to
180 degrees

order of operations
 parentheses first (innermost to outer)
 exponents or radicals
 multiplication and division
 addition and subtraction

percent formula
part= percent x whole

percent increase
percent increase= amount of increase/ original whole x 100%

percent decrease
percent decrease= amount of decrease/original whole x 100%

how to recognize if multiples of 2
last digit is even

how to recognize if multiples of 3
sum of digits is a multiple of 3

how to recognize multiples of 4
last two digits are multiples of 4

how to recognize multiples of 5
last digit is 5 or 0

how to recognize mulitples of 6
sum of digits is a multiple of 3 and last digit is even

how to recognize multiples of 9
sum of digits is a multiple of 9

how to recognize multiples of 10
last digit is 0

how to recognize multiples of 12
 sum of digits is a multiple of 3 and last two digits are a multiple of 4

average
average= sum of terms/ number of terms

using average to find sum
sum=(average) x (number of terms)

how to find the number of integers from A to B inclusive
BA+1

median
put the numbers in numerical order and take to the middle number

mode
take the number that appears most often

range
take the positive difference between the greatest and least values

probability
probability= number of favorable outcomes/ total number of possible outcomes

polynomial
an expression consisting of the sum of two or more terms

inequalities
remember to reverse the inequality sign if you multiply or divide by a negative quality

absolute value
the distance the number is from zero to the number on the number line, absolute value is always positive

area of a triangle
are= 1/2 (base)(height)

isosceles triangles
two equal sides and two equal angles

equilateral triangles
three equal sides and three 60 degree angles

similar triangles
corresponding angles are equal and corresponding sides are proportional

how to find the hypotenuse or leg of a right triangle
 pythagorean theorum
 a^{2}+ b^{2}= c^{2}

special right triangles
 3:4:5
 5:12:13
 30 degree: 60 degree: 90 degree
 45degree: 45 degree: 90 degree
 1: √3: 2
 1:1:√2

perimeter of rectangle
perimeter= 2(length + width)

area of rectangle
area= (length)(width)

area of square
area= side^{2}

area of parallelogram
area= (base)(height)

area of trapezoid
break figure into rectangle and triangle

circumference of a circle
circumference= 2(pie)r= (pie)d

area of circle
area= (pie)r^{2}

slope of line
slope= rise/run= change in y/change in x

simple interest problem
interest= (principal) x (interest rate)x time
 interest rate is expressed as decimal
 time is in years or fraction of years

finding compound interest
(final balance)= (principal) x (1+ interest rate/C)^{(time x C)}
c= number of times compounded annually

find average rate
average A per B= Total A/Total B

average speed
average speed= total distance/ time

combined work problem
1/r + 1/s= 1/t
 r and s are number of hours it would take two people to complete work
 t is the total time