Integer Properties Flashcards
When picking numbers
If there are multiple numbers that satisfy the constraints, pick at least 3 examples
Identifying factors
- Approximate the square root
- 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)
- Count the “factor buddies” as well
Is 1 a prime number?
NO
Is 2 a prime number?
YES
Prime numbers under 30
2, 3, 5, 7, 11, 13, 17, 19, 23, 29
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)
Short cut for determining whether a number less than 100 is prime
Test 2, 3, 5, and 7
The number of prime numbers…
…is infinite
Square of any prime number…
…has exactly three factors
Any division problem with a QUOTIENT of 0…
…can have a remainder (2/7 has a remainder of 2).
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)