Quantitative Flashcards
Integers
Any counting number including negative numbers (e.g. -3, -1, 2, 7…but not 2.5)
Real Numbers
Numbers that appear on the number line (i.e., one that is not imaginary) including pi, the square root of 2, etc.
Order of Operations
PEMDAS: parentheses, exponents, multiplication/division, addition/subtraction
Prime Numbers
Number that is divisible only by itself and 1. Examples are 2, 3, 5, 7, 11. 1 is not a prime, 2 is the smallest prime and only even prime.
Prime Factorization
The prime factorization of a number is dividing it into its constituent primes. So for 21, this is 3 x 7; for 60, 2 x 2 x 3 x 5. 7644 = 2 x 2 x 3 x 7 x 7 x 13.
Greatest Common Factor (aka greatest common divisor)
The biggest factor shared by the two given numbers. The GCF of 12 and 30 is 6 – it is the biggest divisor they both share. If two numbers share no primes, the GCF is 1.
Least Common Multiple
The smallest positive integer between two numbers as a factor. The LCM of 4 and 6 is 12 – it is the smallest number that has both 4 and 6 in its divisors.
Absolute Values
The absolute value of a number is its distance from a number line (no negatives).
|x| = x, |-x| = x
Percentages
Percent is per 100. To find what percent some part of a whole use:
part / whole = percent / 100
Percent Change
Percent change: % change = change/original value
If the price of something goes from $40 to $52, the percent change is:
(52-40)/40 = 12/40 = 3/10 = 30/100 = 30%
Roots: Perfect Squares
Numbers with integers as their square roots: 4, 9, 16, 25, etc.
Roots: Cube roots
3√x is a number that, when cubed, equals x.
Example 3√-8 = -2.
Roots: Adding roots
2√7 + 9√7 = 11√7.
Roots can be added like variables.
Statistics: Mean, Median, Mode
Mean = average, total sum / n Median = middlemost value when numbers are arranged in ascending order; for an even amount of numbers, take the average of the middle two Mode = the number that occurs most frequently
Statistics: Standard Deviation and Variance
The standard deviation represents the average distance the data values are away from the mean. Variance = SD^2
Counting: Combinations
nCr = n! / r!(n - r)!
Example: 5c3 = 5! / 3!(2!) = 10
When the order does not matter – for example, picking any 3 friends from a group of 5.
Counting: Permutations
nPr = n! / (n - r)!
When the order does matter – for example, how many ways you could order 3 letters from the word PARTY?
Probability: Formula
Probability that event A will happen:
P(A) = number of outcomes where A occurs / total number of outcomes
Formulas: Area of Square
A = s x s (s = side)