# Hot Math How-Tos

### How To: Find the Radius of a Circle from Arc Length

The video provides two example problems for finding the radius of a circle given the arc length. Problem one finds the radius given radians, and the second problem uses degrees.

### How To: Find Leg Lengths and Hypotenuse of a 45 45 90 Triangle

A 45 45 90 triangle is a special right triangle because you can use short cuts to find leg length and hypotenuse length. This video solves two problems involving leg length and hypotenuse length.

### How To: Factor trinomials using the Berry factoring method

In this free video math lesson YAY MATH, we learn how to factor trionmials using the Berry method. With mathematics, as with anything else, not everyone progresses at the same rate. Algebra is no exception. Happily, in the age of Internet video tutorials, this isn't a problem. Those who progress quickly can go beyond what's being taught them and those who are struggling likewise have all the time in the world to catch up. Whether you need help finishing your homework or studying for that next...

### How To: Evaluate factorials with a TI-83 calculator

The factorial of a number n can be defined as the product of all positive integers that are greater than 0 but less than or equal to n.

### How To: Use a unit circle to find trig values

In this tutorial, we learn how to use a unit circle to find trig values. The unit circle has a radius one, use the definition of the trig functions to figure this out. Write them down if you need to, to remember what they are. You will also need two special triangles to help figure this out. Make sure you know the short side is opposite 30 degrees. Now, draw out your graph and find the ordered pair of pie, then find the y value of it. From here, find the cosine, tangent, and other units using...

### How To: Identify number types

In this video, we learn how to identify number types. You will need to figure out what numbers from a list is a rational numbers in your math equations. A natural number is a counting number (1,2,3). A whole number is a natural number and zero (0,1,2,3). An integer is a whole number and a negative whole (-2,-1,0,1,2). A rational number is any number that can be expressed as a ration of integers. An irrational number is any number that's not rational and non-perfect. Once you understand these ...

### How To: Calculate standard deviation with graphing calculator

This video tutorial is in the Education category which will show you how to calculate standard deviation with TI graphing calculator. First you got to enter the data in to the calculator. Go to stat and click on enter. This will edit a list. Now you type in these numbers: 50, 20, 33, 40 and 55. Then press stat and click on enter. This will bring up the 1-var stats page. Press the "2nd" button and L1, because all our data is in L1. Click on enter and you will get all the data that you will nee...

### How To: Add mixed numbers

A mixed number is just another way of expressing a fractional number. This video shows two methods by which two mixed numbers may be added.

### How To: Change decimals to fractions

In this tutorial, we learn how to change decimals to fractions. First, you will take your decimal and put it over 1. Any number divided by 1 will be that number that you started with. To get rid of the decimal, you can multiply it by hand and moving the numbers to the left. To keep the number the same, you also have to multiply the bottom of the fraction by the same number. Now, you can just simplify the fraction and you will end up with the correct number! This is easy to do and is a great b...

### How To: Find the area of a trapezoid

In this video, we learn how to find the area of a trapezoid. The formula to figure out how to find the answer is: Area= 1/2x (base1 x base2) x height. Now, find the bases and the height of the trapezoid. Remember that the height must always be perpendicular to the bases. Once you have found these, add the bases and multiply by the height. You can use a calculator to do this or do it off hand if you're good with math. For the third step, divide the answer by 2 and then write down the answers w...

### How To: Determine if a point lies on a line in standard form

In this video, we learn how to determine if a point lies on a line in standard form. In order to do this, you will need to substitute the X and Y value with the ordered pair that is given. The X value is the first number and the Y value is the second number. Re-write your equation, substituting in the numbers to the appropriate spots. Now, simplify the equation by doing multiplication with the negatives and positives (if given). When you get through the equation, you will end up with the solu...

### How To: Multiply fractions easily

In this tutorial, we learn how to multiply fractions easily. First, you will need to know where the numerator and denominator are in the equation. Numerator is on top and Denominator is on the bottom. When you multiply fractions, you multiply the top and then the bottom of the fractions straight across. Once you have multiplied them, you will write your number out as a fraction. Make sure you reduce your fraction as much as you can, or else it will not be a correct answer. To reduce it, see w...

### How To: Find how many toothpicks will be needed to form the nth figure in a sequence

From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps. With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to employ inductive reasoning to determine the number of toothpicks you'll require to generate the nth (e.g., the 50th) figure in a sequence of figures.

### How To: Solve word problems involving units of weight in basic math

From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps. With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to solve application problems involving units of weight in basic arithmetic.

### How To: Divide mixed numbers

In order to divide mixed numbers, you should change the mixed numbers into improper fractions. With the problem 5 Â¼ divided by 2 3/8, you should convert both mixed fractions to improper fractions. 5 Â¼ becomes 21/4, when you multiply 4 times 5 and add one. 2 3/8 becomes 19/8, when you multiply 8 times 2 and add 3.

### How To: Subtract fractions with like denominators in basic math

From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to subtract fractions with like denominators in basic math.

### How To: Reduce fractions to their lowest terms

This video tutorial belongs to the Education category which is going to show you how to reduce fractions to their lowest terms. For doing any operation with fractions like addition, subtraction, multiplication or division, they need to be reduced to their lowest terms. To do this look at the numerator and the denominator and decide what number can divide both of them. Continue dividing till you can no more divide them. Now you get the lowest term of the fraction. For example, 2/4 can be divid...

### How To: Find the circumference of a circle

In this video tutorial, viewers learn how to find the circumference of a circle. This task is very easy, simple and fast to do. To find the circumference of a circle, multiple Pi with the diameter of the circle. The value of Pi is 3.14. The diameter is equal to 2 times the radius. Simply multiply the radius by 2 to find he diameter. The diameter is the straight horizontal line in the center of a circle. This video provides a demonstration for viewers to easily understand and follow along. Thi...

### How To: "Back out the tax" from a receipt

In this video, we learn how to back out the tax from a receipt. If you have a receipt where you see how much you paid and know the tax rate, except you want to figure out the cost of the item before the tax. First, take the cost of the item including tax and what the tax rate is. To figure out the original price, let x equal the cost of the item. Add the tax to the cost of the item which will equal the cost you paid. Perform the equation 1x+(tax rate)= (total price). After you figure this equ...

### How To: Find the area of a square or rectangle in geometry

In this video tutorial, viewers learn how to find the area of a rectangle. The formula for finding the area of a rectangle is: A= b x h. The base is the horizontal bottom lie of the rectangle and the height is the vertical straight line of the rectangle. Whenever working with area, users must square the unit of measurement. To find the area of a square, multiple the side of the square twice (square it). This video will benefit those student viewers who are struggling with math, and are in nee...

### How To: Solve rational expression simplification word problems

From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to unpack and solve word problems that require you to simplify rational expressions.

### How To: Multiply math fractions

Math is one of those subjects in school where you either love it or hate it or just don't get it. But math is nothing to fear, because it's a part of our everyday lives, and ifs something everyone should know the basics of. Don’t let math intimidate you. Whether you’re multiplying two fractions or a fraction and a whole number, solve the problem without a calculator in just a few steps.

### How To: Find the 100th term in a sequence

Need to find the nth term in a given arithmetic sequence? See how it's done with this free video math lesson. Need help finding the From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's seri...

### How To: Learn to calculate percent error with this music video

Math, chemistry, physics can all be a very difficult thing to understand. But if you have the right teacher, then it can make life a bit easier. Maybe even a music video explaining it can be a bit easier. In this tutorial, if you're having a tough time with calculating the percent error, this music video may be what you need. So check it out and good luck!

### How To: Solve percentages without a calculator

Want to know how to find percentages quickly without the use of a calculator? It's easy. This free video math lesson will show you how it's done. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just study for that next big test).

### How To: Use the quadratic formula to solve algebraic equations

Using the quadratic formula to solve equations may bring one, two, or no algebraic solutions. The quadratic formula is special to quadratic equations, which can have fractions, radicals, or neverending decimals. Learn how to solve quadratic equations using the quadratic formula with this free video algebra lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's ea...

### How To: Evaluate expressions involving absolute value

Need to know how to evaluate expressions involving absolute values? It's an absolute cinch. Learn how with this free video math lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this free math tutorial, you'll learn how to solve problems with ab...

### How To: Use interval notation to express inequalities

Could you use a little help figuring out how to use interval notation to express inequalties? Watch this free video lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this free math tutorial, you'll learn how to give inequalities in interval nota...

### How To: Evaluate numbers raised to fractional exponents

Looking for instructions on how to evaluate numbers raised to fractional powers? Learn how with this free video lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this free math tutorial, you'll learn how to solve problems involving numbers raise...

### How To: Solve equations with the order of operations

In mathematics, the order of operations define the priority in which complex equations are solved. The top priority is your parenthesis, then exponents, followed by multiplication and division, and finally addition and subtraction (PEMDAS). This video tutorial demonstrates the order of operation with various examples and explains the associated methodology. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autod...

### How To: Simplify & solve multi-step equations in algebra

Looking for a primer on how to combine like terms and/or use the distributive property to solve algebraic equations? Learn how with this free video lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test).

### How To: Prove Rank(A) = Rank(transpose of A) in linear algebra

Learn how to prove that the rank of a matrix, A, is equal to the rank of its transpose in linear algebra. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test).

### How To: Find a transformation matrix with respect to a basis

Learn how to find a transformation matrix with respect to a non-standard basis in linear algebra. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test).

### How To: Simplify and rewrite the complex number "i"

The powers of the complex number "i" run their course in a cyclical nature, like annual seasons of "American Idol." Simplify your life - or at least your math class life - by learning how to rewrite the powers of "i" into simple, single variable expressions.

### How To: Rewrite radicals using complex numbers

A complex number is half real (a) and half imaginary (bi), just like that Edward Cullen who makes your heart thump realistically but whose sparkly chest makes you wonder if he's something more.

### How To: Simplify complex fractions in algebra

Being circuitous and using ample euphemisms has gotten many a politan elected by the dumb and hated by the knowing. Though embellishing speech is often preferred in jovial presidential debates, mathematicians prefer to cut out the fat and get straight to the point.

### How To: Find partial derivatives of vector-valued functions

From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to find the partial derivative of a vector-valued function in linear algebra or vector c...

### How To: Graph an inequality in slope-intercept form

This how to video shows you how to graph an inequality in slope intercept form. First, graph the line. Depending on the inequality, use a dash or solid line. Use a solid line for less than or equal to or greater than or equal to. Use a dash line for greater than or less than. If y is less than or less than or equal to, shade the bottom area of the line. If it is y is greater than or greater than or equal to, shade the top area of the line. Check your answer by substituting in any point from t...

### How To: Solve equations with algebraic variables on both sides

In basic algebraic equations all the variables are on left side of the equation. But as the complexity of the problems increases you will find that the equations will contain variables on both sides of the equation. To solve these kinds of problems first simplify the equations on each side of the equation. You can use the distributive law to do this. Next try to cancel the variable on the right side of equation by adding the negative value of that variable to both the sides of the equation. N...

### How To: Find the surface area of an aluminum can or cylinder

This video tells us the method to find the surface area of an aluminium can or cylinder. The surface area includes the outside area of the curved portion and the aluminium top and bottom. The formula to find area is the multiple of 2, pi, r, r+h or (2)(pi)(r)(r+h). The radius of the cylinder is the radius of the circular top or bottom. In the example shown in the video, the radius is 4 inches and the height is 12 inches. Substituting the values in the formula, we get the surface area as (2)(3...