Pre Algebra

Multiplication and Division

1. Explain Communicative property of Multiplication and provide an example.
  • The commutative property states that the order of multiplication does not matter.
  • Mathematically, it can be expressed as: $a \times b = b \times a$
  • For example: $3 \times 4 = 4 \times 3 = 12.$
2. Explain Associative property of Multiplication and provide an example.
  • The associative property states that the grouping of numbers in a multiplication operation does not affect the result. You can change the grouping (i.e., which numbers you multiply together first) without changing the final product.
  • Mathematically, it can be expressed as$: (a \times b) \times c = a \times (b \times c)$
  • For example, $(2 \times 3) \times 4 = 2 \times (3 \times 4) = 24.$
3. Explain Multiplication Distributive property and provide an example.
  • The distributive property states that multiplying a number by the sum (or difference) of two other numbers is equivalent to multiplying the number by each of those two numbers separately and then adding (or subtracting) the results.
  • Mathematically, it can be expressed as: $a \times (b + c) = (a \times b) + (a \times c)$
  • For example, $4 \times (2 + 3) = (4 \times 2) + (4 \times 3) = 20.$
4. Explain the concept reciprocal of division and multiplication and provide an alternative of writing $ a ÷ b$
  • The reciprocal of a number is essentially its multiplicative inverse. It states that division of two numbers can be rewritten as multiplication of one number by the reciprocal of the other number
  • $a ÷ b == a × \frac{1}{b}$
5. Explain the phrase “Taking the reciprocal of a number” and provide an example.
  • Taking the reciprocal of a number means finding another number such that when you multiply them together, you get 1.
  • Example: Taking a reciprocal of 2 is $\frac{1}{2}$.
6. Provide the reciprocal of 8.
$\frac{1}{8}$ because $8 \times \frac{1}{8} =1$

Factors and Multiples

1. A factor of a number (b) leaves no remainder when it is divided by that number (a). Express this in mathematical notion:
  • If “a” is a factor of “b,” then “a” divides “b” evenly.

  • Express it as $a \times x = b$

    Where:

    • $a$ is the factor.
    • $x$ is some other whole number.
    • $b$ is the original number.
2. Explain what it means that the number “a” is said to divide evenly into another number “b,”
  • It means that when you perform the division operation $b ÷ a$, the result is a whole number without any remainder.
3. Explain Factorisation and give an example.
  • Express a number or algebraic expression as a product of its factors.
  • Example: Factorisation of 12 is $2\times2\times3$
4. Explain greatest common factor (GCF) and give an example.
  • The GCF of two or more numbers is the largest number that evenly divides each of them. It is also known as the greatest common divisor (GCD).
  • Example, the GCF of 12 and 18 is 6.
5. Explain common factors.
Common factors are factors that two or more numbers share.
6. Explain the term multiples.
A set of numbers that are obtained by multiplying a base number by other whole numbers.
7. 15 is a multiple of 3 and 3 is not a multiple of 15. Explain why the sentence is correct.
  • 15 is a multiple of 3 because 3 can be multiplied by a whole number to give us 15 without any remainder.
  • However, 3 is not a multiple of 15 because there is no whole number that can multiply by 15 to get 3 without any remainder.

Number Types

1. Natural (N): Provide the definition and example.
  • Any positive numbers and not inclusive of 0.
  • Example(s): 1, 2, 3.
2. Whole Number (W): Provide the definition and example.
  • Number 0 and any positive number and that can be written without fractional component (0,1,2,3)
  • Example(s): 0, 1, 2, 3 ..
3. Integer Number (Z): Provide the definition and example.
  • Any number (positive and negative and 0.) that can be written without fractional component
  • Example(s): -3, -2, -1, 0, 1, 2, 3 ..
4. Rational Number (Q): Provide the definition and example.
  • Numbers that can be expressed as fractions. N/D, where N and D are both integers and the D is not 0.
  • Example(s): $\frac{1}{2},-\frac{3}{5}$
5. Irrational Number: Provide the definition and example.
  • Irrational numbers cannot be expressed as fractions with integers in the numerator and denominator, and their decimal representations neither terminate nor repeat.
  • Example(s): $\pi$
6. Real Number (R): Provide the definition.
  • Real numbers include all rational and irrational numbers. They represent all possible points on the number line.
7. Composite Number: Provide the definition and example.
  • Natural numbers that can be formed by multiplying at least 2 smaller natural numbers. They can be divided evenly by numbers other than 1 and themselves.
  • Example(s): 4,6,8,9,10
8. Prime Number: Provide the definition and example.
  • Prime numbers are natural numbers greater than 1 that have exactly two distinct positive divisors: 1 and themselves.
  • Examples(s): 2, 3, 5, 7, 11
9. Provide the only even prime number.
2 because that is the only even number that has two exact distinct positive divisors: 1 and itself.
10. Explain why 1 is not a prime number.
To qualify as a prime number, the number must have exactly two distinct positive divisors: 1 and themselves. Therefore 1 is not a prime number because it is only divisible by itself (1 number) and that is all.

Ratios, Rate and Percent

1. Explain the term ratio, use-case and the common expression.
  • Ratio is used to compare two quantities / amounts.
  • Ratios are used to describe the relative sizes or quantities of different things
  • The most common expression is in fraction. In a ratio $a:b$.
2. Explain the ratio $a:b = 2:3$
It implies a proportional relationship between two quantities. It means for 2 units of $a$ you would have 3 units of $b$.
3. Explain the term rate, use-case and the common expression.
  • Rate is a measure of how one quantity changes in relation to another quantity.
  • Rates are often used to describe how something varies or moves with respect to time, distance, or other variables.
  • Rates are typically expressed as a ratio of two quantities, where one quantity represents the change or movement.
4. Explain the difference between ratios and rates(Comparison and dimension). Provide examples.
  • Differences:
    • Ratios are used to compare relative size or quantities between two or more things. Whereas rate are used to describe how one quantity changes in relation to another quantity.
    • Ratios are dimensionless and do not have units. Ratios are expressed as a quantity divided by another quantity with units, making them dimensionally consistent)
  • Examples:
    • Ratio of 2:3
    • Rates: “Per Unit of Time” / “Miles per Hour”
5. Explain percentages in the context of ratios.
A percentage can be thought of as a special type of ratio where the denominator is always 100. The numerator of the ratio is part of the whole.
6. Define percentage.
Percentage is a way of expressing a number or ratio as a fraction of 100.
7. Given a ratio $10:20$ boys to total number of students, what is the percentage of the students that are boys?
$\frac{10}{20}\times 100$% $= 50$%
8. Explain proportional relationships. Provide an example of proportional relationship.
  • A relationship between two variables where the ratio of their corresponding value is constant.
  • Ratio of $2:3$ is the same as the Ratio of $4:6$
9. Provide a general expression to represent proportional relationship.
  • $y=kx$
  • Where:
    • y = value of the first variable,
    • x = value of the second variable
    • k = constant of proportionality (What do you do to multiple x to get to y?)
10. How many bottles are required to clean the bathroom. If $\frac 35$ bottle cleans $\frac 13$ bathroom?
$\frac{3}{5} \times 3 = \frac{9}{5}$
11. How many bottles are required to clean the bathroom. If $\frac 35$ bathroom needs $\frac 13$ bottle solution?
$\frac{1}{3} *\frac{5}{3}= \frac{5}{9}$

Exponent and Roots

1. Define exponents.
Exponent is a repeated operations of multiples
2. List the exponent properties.
  • Power of powers

    $a^m \cdot a^n = a^{m + n}$

  • Quotient of powers

    $\frac{a^m}{a^n} = a^{m - n}$

  • Zero Exponent

    $a^0 = 1 , \text{(for } a \neq 0 \text{)}$

  • Negative Exponent

    $a^{-n} = \frac{1}{a^n}$

  • Fractional Exponent

    $a^{\frac{1}{n}} = \sqrt[n]{a}$

  • Exponent of 1

    $a^1 = a$

  • Exponent of -1

    $a^{-1} = \frac{1}{a}$

3. Explain why does the Zeroth power always leads to 1.
  • The rule that any nonzero number raised to the power of zero is equal to 1 is a mathematical convention and it is established to maintain consistency
  • For example: $a^{m+0} = a^m \cdot a^0 =a^m \cdot1$
4. Provide the intuition of the negative exponent $x^{-n} = \frac{1}{x^n}$.
When base $x$ raised to the power of a positive exponent, we multiply $x$ by itself $n$ times. Conversely, when we raise to the power of a negative exponent, we inverse the operation by dividing $x$ by itself $n$ times.
5. Provide the equal representation of $x^\frac{1}{2}$.
$x^{\frac{1}{2}} = \sqrt{x}$
6. Provide the equal representation of $x^{\frac{a}{b}}$
$x^{\frac{a}{b}} = \sqrt[b]{x^a} = (x^a)^\frac{1}{b} = (x^\frac{1}{b})^a$
7. Define square root. Provide an example.

A square root of a number “x” is a value “y” such that when “y” is multiplied by itself, it equals “x.” In mathematical notation, if $y^2 = x$, then $y$ is the square root of $x$.

Example: The square root of $25$ is $5$ because $5^2 = 25.$

8. Define the product property of square roots.

$\sqrt{ab} = \sqrt{a} \cdot \sqrt{b}$

This property allows you to split the square root of a product into the product of the square roots of the individual factors.

9. Simplify $\sqrt{12}$ using the product property of square root.
$\sqrt{12} = \sqrt{(4 * 3)} = \sqrt{4}* \sqrt{3} = 2\sqrt{3}$
10. Define the quotient property of square roots.

$\sqrt{a \div b} = \sqrt{a} \div \sqrt{b}$

This property enables you to split the square root of a quotient into the quotient of the square roots of the numerator and denominator.

11. Simplify $\sqrt{\frac{9}{4}}$ using the quotient property of square root.
$\sqrt{9} \div \sqrt{4} = 3 \div2$
Last updated on 19 Nov 2023