Chapter 7: GMAT Math, Basic Principles
Integers
-Numbers we think of when we think of numbers -Can be positive or negative -NOT fractions -incl zero
What numbers are not prime?
0 & 1
Prime numbers 0-100
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97
divisible by 5
Ends in 0 or 5
Two
Least & only even prime number
Positive * Negative =
Negative
Positive * Positive=
Positive
What is another name for the ones digit?
Units digit
every integer > 1 is...
both its own greatest factor and least positive integer
divisible by 6
divisible by both 2 & 3
even * even =
even
even + even =
even
even*odd=
even
odd+odd =
even
Least common multiple
if x is is divisible by two integers, x is a common multiple of them. this is the lowest of these
consecutive numbers
integers listed in order of increasing value w/o any integers missing in between
when 0 is divided by something
it equals 0
divisible by 4
last 2 digits divisible by 4
distinct numbers
numbers that cannot be equal
even + odd =
odd
odd * odd =
odd
Divisible by 2
ones divisible by 2
Zero
only number that is neither + or -, even #.
Negative * Negative =
positive
divisible by 3
sum of digits divisible by 3
Absolute Value
the distance between x & 0
what is it called when something is divided by 0?
undefined (won't see this on test! is 0 in denim, you've done something wrong!)
prime factors
use a factor tree. ALL positive integers > 1 have unique prime factorizations (frequently tested).
greatest common factor
when 2 integers are both divisibly by x then x is a common factor. this is the greatest to these. factor to find answer.
Divisible
when y/x leaves no remainder
factor
x is a ________ of y if y is divisible by x