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Integers
- - Whole number
- - positive or negative
- - 0 is an integer (neither positive or neg)
*does not include fractions
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Consecutive Integers
Listed in increasing size w/o any integers missing in between
- Formula:
- n, n+1, n+2, n+3, etc...
Even: -2, 0,2,4,6,8
Odd: -3, -1, 1, 3, 5
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Distinct
mathematical way of saying "different"
- ex. Count the distinct prime factors of 12 = 2 and 3
- 12 = 2 x 2 x 3 (can only count 2 once)
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Digits
Ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
All digits are integers
Most likely: count digits or supply the missing digits
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Prime numbers
Divided evenly only by itself and i
All prime number are positive
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Positive & Negative
- Multiplication
- pos x pos = pos
pos x neg = neg
neg x neg = pos
- Addition
- pos + neg = 4 + (-3) = 1
neg + neg = -3 + -5 = -8 (treat it like pos)
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Odd & Even
- Even - divided by 2
- ~ 0 is considered even
Odd - can not be divided evenly by 2
- even x even = even
- odd x odd = odd
- even x odd = even
- even + even = even
- odd + odd = even
- even + odd = odd
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Prime number
- positive integer that can be divided evenly only by two distinct factors: 1 and itself
- neither 1 or 0 is prime
- all primes are positve
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Factors and Multiples
"Factors are few; multiples are many"
- Factor - divided evenly into a number
- Multiple - result of a number mutiplying another
- Example:
- Factors of 15 = 1, 3, 5, 15
- Multiple = 15 is a multiple of 3; 12 is a multiple of 3
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Absolute Value
distance between the number and 0
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Divisibility Rules
Useful divisibility shortcuts:
2 - unit digit can be divided evenly by 2
3 - sum of digits can be divided by 3 easily
4 - the last two digits of the number can be divided by 4
5 - final digit is either 0 or 5
6 - if it divisible by both 2 and 3
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