GRE basic math concepts
an integer is divisible by 3 if - ANS-its digits add up to a multiple of 3
an integer is divisible by 4 if - ANS-its last two digits are a multiple of 4
an integer is divisible by 5 if - ANS-its last digit is 0 or 5
an integer is divisible by 6 if - ANS-it is divisible by both 2 and 3
an integer is divisible by 9 if - ANS-its digits add up to a multiple of 9
Distinct - ANS-ex:
12 has three prime factors (2,2, and 3), but only 2 distinct factors (2 and 3).
Division by zero is - ANS-undefined or "it can't be done" also applies to zero as the
denomotor.
element - ANS-one of the membres of a set
how to find lowest common multiple - ANS-break down both integers into their prime
factorizations, and make a venn diagram of the results. Multiply all the numbers in the
diagram
ex:
36=(2)(2)(3)(3), and 48= (2)(2)(2)(2)(3)
36->(3 [2,2,3] 2,2)<-48
LCM= 3x2x2x3x2x2 =
how to find the greatest/highest common factor - ANS-break down both integers into
their prime factorizations, and multiply all the prime factors they have in common.
ex:
36=(2)(2)(3)(3), and 48= (2)(2)(2)(2)(3)
GCF= (2)(2)(3)= 12
multiplying or dividing two numbers with different signs gives a - ANS-negative result
an integer is divisible by 3 if - ANS-its digits add up to a multiple of 3
an integer is divisible by 4 if - ANS-its last two digits are a multiple of 4
an integer is divisible by 5 if - ANS-its last digit is 0 or 5
an integer is divisible by 6 if - ANS-it is divisible by both 2 and 3
an integer is divisible by 9 if - ANS-its digits add up to a multiple of 9
Distinct - ANS-ex:
12 has three prime factors (2,2, and 3), but only 2 distinct factors (2 and 3).
Division by zero is - ANS-undefined or "it can't be done" also applies to zero as the
denomotor.
element - ANS-one of the membres of a set
how to find lowest common multiple - ANS-break down both integers into their prime
factorizations, and make a venn diagram of the results. Multiply all the numbers in the
diagram
ex:
36=(2)(2)(3)(3), and 48= (2)(2)(2)(2)(3)
36->(3 [2,2,3] 2,2)<-48
LCM= 3x2x2x3x2x2 =
how to find the greatest/highest common factor - ANS-break down both integers into
their prime factorizations, and multiply all the prime factors they have in common.
ex:
36=(2)(2)(3)(3), and 48= (2)(2)(2)(2)(3)
GCF= (2)(2)(3)= 12
multiplying or dividing two numbers with different signs gives a - ANS-negative result
