Topics include integers, such as divisibility, factorization, prime numbers, remainders, and odd and even integers; arithmetic operations, exponents, and roots; and concepts such as estimation, percent, ratio, rate, absolute value, the number line, decimal representation, and sequences of numbers.
Integers Properties of Integers - Integer: Number with no fraction or decimal.
- An integer can be positive, negative, or 0.
EX: -2, 0, 18
Identity Properties - A number will not change when adding 0 to the number.
EX: 8 + 0 = 8
EX: y + 0 = y
- A number will not change when multiplying it by 1.
EX: 6 × 1 = 6
EX: y × 1 = y
Properties of Zero - Any number multiplied by 0 is 0.
- If the product is 0, one or more of the factors must equal 0.
EX: a ×
b ×
c ×
d = 0
a, b, c, or d must equal 0.
- If the product is not equal to 0, none of the factors equals 0.
EX: a ×
b ×
c ×
d ≠ 0
a, b, c, and d ≠ 0.
Divisibility - An integer is divisible by 2 if the last digit in the integer is divisible by 2.
EX: 8,542,634
4 is divisible by 2.
Therefore, 8,542,634 is divisible by 2.
- An integer is divisible by 3 if the sum of the digits in the integer is divisible by 3.
EX: 865,257
8 + 6 + 5 + 2 + 5 + 7 = 33
33 is divisible by 3.
Therefore, 865,257 is divisible by 3.
- An integer is divisible by 4 if the last digit in the integer is divisible by 4.
EX: 5,243,624
24 is divisible by 4.
Therefore, 5,243,624 is divisible by 4.
- An integer is divisible by 5 if the last digit in the integer is 0 or 5.
EX: 6,842,570
The last digit is 0.
Therefore, 6,842,570 is divisible by 5.
- An integer is divisible by 6 if the integer is divisible by both 2 and 3.
EX: 358,416
3 + 5 + 8 + 4 + 1 + 6 = 27
27 is divisible by 3.
6 is divisible by 2.
Therefore, 358,416 is divisible by 6.
- An integer is divisible by 9 if the sum of the digits in the integer is divisible by 9.
EX: 620,874
6 + 2 + 0 + 8 + 7 + 4 = 27
27 is divisible by 9.
Therefore, 620,874 is divisible by 9.
Odd & Even Integers - A number is even if the last digit in the number is 0, 2, 4, 6, or 8.
EX: 6,584,298
The last digit of the number is 8.
Therefore, 6,584,298 is even.
- A number is odd if the last digit in the number is 1, 3, 5, 7, or 9.
EX: 2,451,869
The last digit of the number is 9.
Therefore, 2,451,869 is odd.
- An even integer can be represented as 2k, where k is an integer.
- An odd integer can be represented as 2k + 1 or 2k – 1, where k is an integer.
Rules for Adding & Multiplying Odd & Even Numbers - Odd + Odd = Even
- Even + Even = Even
- Odd + Even = Odd
- Odd × Odd = Odd
- Even × Even = Even
- Odd × Even = Even
Prime Numbers & Factors - Factors of an integer are integers that can be divided evenly into the integer.
EX: The factors of 24 are 1, 2, 3, 4, 6, 8, 12, and 24.
- Prime number: Number that can only be divided evenly by itself and 1.
EX: 19 is a prime number.
- The prime numbers up to twenty are 2, 3, 5, 7, 11, 13, 17, and 19.
- 0 and 1 are never prime numbers.
- 2 is the only even prime number.
Least Common Multiple - The least common multiple of two or more numbers is the smallest number that is a multiple of each of the original numbers.
EX: The least common multiple of 3 and 13 is 39.
The multiples of 3 are 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, etc.
The multiples of 13 are 13, 26, 39, etc.
39 is the smallest number that intersects these lists.
Exponents