Integer Properties Flashcards Preview

GRE 2017 > Integer Properties > Flashcards

Flashcards in Integer Properties Deck (11):
1

When picking numbers

If there are multiple numbers that satisfy the constraints, pick at least 3 examples

2

Identifying factors

1. Approximate the square root
2. Test the divisibility rules for every integer less than or equal to the square root (start with 1 and stop when you reach the square root)
3. Count the "factor buddies" as well

3

Is 1 a prime number?

NO

4

Is 2 a prime number?

YES

5

Prime numbers under 30

2, 3, 5, 7, 11, 13, 17, 19, 23, 29

6

To determine whether a large number is prime

(Use the identifying factors - approximate the square root, go from 1 to the square root and use the divisibility rules)

7

Short cut for determining whether a number less than 100 is prime

Test 2, 3, 5, and 7

8

The number of prime numbers...

...is infinite

9

Square of any prime number...

...has exactly three factors

10

Any division problem with a QUOTIENT of 0...

...can have a remainder (2/7 has a remainder of 2).

11

To solve more difficult remainder problems

...find several integers that produce a certain remainder.
1 - generate 3 multiples of your divisor
2 - add the remainder to each

(E.g., to find integers that leave a remainder of 3 when divided by 7, pick some multiples of 7 (7, 14, 21) and add 3 to each of them (10, 17, 24)