# Math Semester Final How-Tos

### How To: Ratios & Unit Rates

What Is a Rate? A rate is a comparison of two quantities that have different units. An example is 90 miles/3 hours, which is read as 90 miles per 3 hours.

### How To: Scale Factor

What Is Scale Factor? Scale factor is the ratio of the length of the scale drawing to the corresponding length of the original object.

### How To: Check for Proportions

What Are Proportions? Proportions are 2 ratios that are equal.

### How To: Pythagorean Theorem

What Is Pythagorean Theorem? Pythagorean Theorem is an equation discovered by a man named Pythagoras. It can be used to determine whether or not a triangle is a right triangle and find missing lengths of a triangle. The equation is: Parts of a Triangle

### How To: Rational & Irrational Numbers

What Is a Rational Number? A rational number is a number that can be written as a ratio and a/b.

### How To: Solve Equations with Fractions

Solving Equations with Fractions Using Addition In our first example, our equation is b - 11/10 = -13/5

### How To: Find LCM

What Is LCM? LCM is an acronym for "Least Common Multiple." LCM is the smallest number that is a multiple of two or more numbers.

### How To: Do Prime Factorization

What Is Prime Factorization? Prime factorization is finding prime numbers that, when multiplied, equal the original number.

### How To: Divisibility Rules

Look at the image below to learn all about the divisibility rules. Real Life Examples

### How To: Dimensional Analysis

What Is Dimensional Analysis? Dimensional analysis is used to convert units. It's the process of analyzing units to decide which conversion factor to use. It's used by multiplying units by conversion factors, rates equal to 1.

### How To: Solve Proportions

The Solution The first step to solving proportions is cross multiplying. For example, we are told to solve the proportion 13/3 = x/9. We cross multiply 13 •9 and 3 • x. Remember, the equal sign does not go away, so don't forget about it! The equation is now 3x = 117. We need to isolate the variable so we do 3x ÷ 3, which is x, and 117 ÷ 3, which equals 39. We now know that x = 39. Practice Time

### How To: Estimate Square Roots

What Is a Square Root and a Radicand? A square root is a number that when multiplied by itself, results in its original number. For example, the square root of 16 is 4 because 4 • 4 = 16.

### How To: Find the GCF

What Is GCF? GCF is an acronym for "Greatest Common Factor." GCF is the largest number that can divides evenly into 2 or more numbers.

### How To: Prime & Composite Numbers & Factors

Here, you will learn all you need to know about prime and composite numbers. What Is a Prime Number?