# Hot Math Posts

### How To: Convert fractions to percents in two steps

This video shows you how to easily convert fractions to percents. You can convert fractions to percents in 2 easy steps. The first step is multiplying the fraction by 100 (e.g.. your fraction is 3/5; 3/5 x 100 = 3/5 x 100/1 = 300/5). The second step is reducing the fraction, when possible (e.g.. 3/5 x 100/1 = 300/5 = 60). Don't forget to add the percent sign (%)(you obtained 60%). That's it! Good Luck!

### How To: Write a sum/difference of logarithms as a logarithm

To write the sum or difference of logarithms as a single logarithm, you will need to learn a few rules. The rules are ln AB = ln A + ln B. This is the addition rule. The multiplication rule of logarithm states that ln A/b = ln A - ln B. The third rule of logarithms that deals with exponents states that ln (M power r) = r * ln M. Using these three rules you can simplify any expression that involves logarithms to arrive at a single logarithm. The instructor shows how to apply these rules to a f...

### How To: Draw a rectangle

In this tutorial the author shows how to draw a rectangle with given base b and height h values. First she uses a ruler to draw a horizontal base line of b cm. Now she uses a protractor and marks a 90 degree angle at one end of the line, then draws a straight line of h cm which is the height of the rectangle. Now she finishes the remaining part of the rectangle by drawing similar lines of the other sides. This video clearly explains how to draw a rectangle given the values of its base and hei...

### How To: Interpret a standard deviation

A rough definition of standard deviation is that it is a measure of expressing the observed variations about the average in statistical data i.e. by how much do the observed values vary from the mean. This video continues from the previous solved example and demonstrates the mathematical interpretation of the standard deviation that was calculated. We begin with stating the mean and standard deviation values and then calculating the upper and lower bounds of the data based on the standard dev...

### How To: Factor a trinomial, find the GCF, then group

This lesson describes the method to find the factors of a trinomial, which consists of three terms, by grouping. First of all, factor out the greatest common factor (GCF), and write the reduced trinomial in parentheses. Let the terms of the trinomial be written in order of exponent of the variable. For example, 3(3X2+2X-8) trinomial is written in the order of variable, with 3(GCF) factored out. Now identify the coefficient of the first and last terms, for example in this case, it is 3 and 8. ...

### How To: Know if matrices can be multiplied

In this Education video tutorial you will learn how to know if matrices can be multiplied. If the column of the first and the row of the second match, you can multiply them. For example if, matrix A has 2 rows and 3 columns (A: 2x3) and matrix B has 3 rows and 4 columns (B: 3x4), then you can multiply them. But, if A: 3x2 and B: 3x4, you cannot multiply them. The shape of the resultant matrix will be the shape of the outer numbers. For example, we saw that if A:2x3 and B :3x2, then they can b...

### How To: Simplify cube roots

In this video, the narrator presents the viewer with a quick, painless way of simplifying cube roots. The narrator presents many methods to simplify square roots to appeal to different learning styles. By doing things like dividing the power by the root to figure out the power of a number x, the viewer is better able to tackle square-rooting numbers that may not have friendly roots. The video gets more complex as it goes on, eventually teaching the viewer to split the inside of a root up if t...

### How To: Find the lowest common multiple/LCM with a factor tree

This video lesson demonstrates how to find the lowest common multiple/lowest common denominator (LCM/LCD) using factor trees. 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: Use the TOA formula in trigonometry

The video is a tutorial in trigonometry. The teacher teaches that the tangent or the tan of an angle is the ratio of the opposite side to the adjacent side of a right angled triangle. If one side and one angle is given then the value of the unknown side can be found by solving the equation tan of angle is equal to opposite upon adjacent side. If the angle is to be found then the tan inverse of the value is seen in the calculator.

### How To: Factor using the ABC method in beginning algebra

Lawrence Perez, from Saddleback College, and his assistant Charlie, give this beginning-algebra two-part lesson on factoring with the ABC method. Solve those darn quadratic equations!

### 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: Figure out the domain of a vector function

Need to know how to calculate the domain of a vector-valued function? 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: Derive the basic area of a triangle

In this video tutorial, viewers learn how to solve the area of a triangle. The formula for the area of a triangle is A = ½ x b x h or bh/2. The base of the triangle is always at the bottom; it is the side that the triangle sits on. The height is the length between the base and the highest point of the triangle. Multiply the base and height of a triangle; then divide by two or multiply by half. The measurement unit of the answer should be squared. This video will benefit those viewers who need...

### How To: Figure out and calculate sales tax

Video describing about how to calculate a sales tax price based on purchase price and sales tax percentage. There is one example which is described as below:

### How To: Solve word problems involving the Pythagorean theorem

See how to solve world problems involving the Pythagorean theorem in geometry with this free video math lesson from Internet pedagogical superstar Simon Khan. 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: Handle missing terms in algebraic long division

In this tutorial you are shown exactly how to do algebraic long division when terms are missing in the polynomial. Follow these steps and you can divide whatever you'd like:

### How To: Solve advanced ratio problems in algebra

Need to know how to solve complex ratio problems in basic 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). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn a system for finding solu...

### How To: Derive and use the slope formula

In this video, we learn how to derive and use the slop formula. The slope of a line is equal to change in y divided by the change in x. First, put the first point on the coordinate point. Then, represent the X and Y by X1 and Y1. Then, put the second point on the plane, representing the coordinates with X2 and Y2. Now, with these two points, draw a straight line and derive the formula from here. The change in X will be from X1 to X2. Now, replace that with the change in X and do the same for ...

### How To: Solve the six problem solution

Solving 6 math problems using different methods is the idea behind this video. First, you make three rows of numbers vertically from 1-9. All the numbers match across for example, 1 1 1, 2 2 2, 3 3 3, and so on. Each set of numbers creates a mathematical problem who's solution is the number six. These problems require some thinking to solve. The only one that is immediately apparent is 2 2 2=6 which is, of course, 2+2+2=6, (3x3)-3=6, the square root of 4 =2. This done on all three of the four...

### How To: Compare methods of solving quadratic equations

In this video the instructor shows the different methods of solving quadratic equations. There are many methods to solve quadratic equations each with its pros and cons, each method suitable for a particular situation. The first method to solve quadratic equation is factoring. The advantage of using this method is that it is quick and easy. But the problem is not all equations can be factored very easily. This method requires a lot of practice and intuition. Use this method when the discrimin...

### How To: Calculate the age of the universe w/ Hubble's constant

This is a great instructional video on how to calculate the age of Universe from Hubble's constant. The speed the galaxy moves away from us is directly proportional to the distance from us. Now think of big bang theory. Hubble's constant is equal to velocity over distance. 1 over Hubble's constant is equal to distance over velocity that is equal to time. Time equals to 1over 71. If you change it into all the same units words it is one over 71000 or 3.09x 10 to the power of 22. It is 3.09x10 t...

### How To: Find the standard error of the mean

In this video the tutor explains about the standard error of the mean. He starts explaining by drawing the diagram of a distribution and now he takes ten samples from the distribution and starts plotting them. He says that in theory if we do it infinite times then we can obtain the sampling distribution of the sampling mean. For the example he takes the number of samples as 10. Now depending on these values of n we can get different sampling distributions. Now he intends to find the mean of t...

### How To: Calculate circular velocity & acceleration

In this video the tutors explain about the concepts of Circular Velocity and Acceleration. She explains the concepts using a real world small experiments. She shows that the equation to calculate circular velocity is v = (2 * Pi * r) / T, where r is the radius of the circle the object moves in, and T being its time period. Now she takes the values from the experiment and calculates the velocity of the other tutor who is the object that runs around in the circle for the experiment. She even co...

### How To: Solve angle problems in geometry

Need some help figuring out how to work with angles in geometry? Look no further. 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 sol...

### How To: Find the geometric mean

It doesn’t matter how long ago your last geometry class was, you can still impress your friends by finding a geometric mean. The geometric mean can be used to find the average of numbers with out unusually high or low results effecting the result.

### How To: Calculate Type I (Type 1) errors in statistics

Need a quick primer on how to solve type-1 error problem in stats? Let this video be your guide. 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. For all of the details, watch this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials.

### How To: Do long division in your head

In this video, we learn how to do long division in your head. Start off by trying to do a division problem in your head that divides evenly. This will help you start to get used to doing division in your head. If you come across a problem where you have to carry a number, don't forget to remember it. If you can see a pattern in any division problem, you will be able to solve any problem that you come across. This can be used for small division problems as well as extremely long division probl...

### How To: Describe a linear system without graphing

This tutorial looks at how to describe a linear system without actually graphing it. In order to do that, you will need to convert both equations of a problem into the Y=mx+b format. Once you have done this, you will be analyzing the m and b values. There are a few rules to follow. If the slopes (or m) and the Y intercepts (or b) are equal, there are an infinite number of solutions (or dependent equations). A second rule is if the slopes are equal and the Y intercepts are different, then the ...

### How To: Understand angle relationships

In this tutorial, we learn how to understand angle relationships. Start out by drawing an angle out and looking at the different parts of it. From here, you will start to find where the different angles are. Linear pairs equal 180 degrees and are on a straight line. Once you learn this, you can write them out on the paper. Supplementary angles equal 180 degrees as well. Two angles that add up to 90 degrees are complimentary angles. Once you learn the relationships between angles, you can bett...

### How To: Convert temperature measured in Celsius to Fahrenheit

This video teaches how to convert a value in Celsius to Fahrenheit in simple steps. First take a paper and marker and keep in mind a Celsius value (e.g-32) to convert into Fahrenheit. Now use the formula to convert Celsius to Fahrenheit which is F=1.8(32)+32. Use a calculator to calculate the formula and you will get the result as 89.6 Fahrenheit. Now round it off the and your final result will be 90 degree Fahrenheit.

### 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: Use log to solve for an unknown variable

Thinking of an unknown exponent as a cat stuck in a tree, you will see how to bring down the exponent by using the the log function. In other words, you will be utilizing the Power Law to bring the exponent down in front of the log function. In this slightly more complicated example, a little work has to be done to first be able to take the log (i.e., get the base by itself). Then once you take the log, the unknown still isn't entirely by itself, so you divide off everything it's being multip...

### Use the quadratic equation: finding the mirror point

In this video the tutor shows how to find the mirror point using a quadratic equation. He says that to graph a parabola you need to find the mirror point symmetrical to the Y-intercept. Now he explains how to find a mirror point using an example with sample values. He begins with saying that the Y-coordinate of the mirror point is same as the Y-coordinate of the Y-intercept. Now you have to find the x coordinate of the mirror point which he shows that it is double the x-coordinate of the vert...

### How To: Draw a dotted/solid line when graphing an inequality

In this video the tutor shows when to use a dotted line and when to use a solid line while graphing lines in coordinate geometry. He says that we should use a dotted line to plot an inequality which contains the symbols less than or greater than. He also says that we should use a straight line when plotting an inequality which contains the signs less than or equal to and greater than or equal to. He goes on and demonstrates this idea with some examples. This video shows how to use different l...

### How To: Find intervals with a TI-83 graphing calculator

Need to know how to use your Texas Instruments graphing calculator for your college math or statistics class? You're in luck... watch this video tutorial to see how to find intervals with a TI-83 graphing calculator.

### How To: Calculate angles formed between parallel lines

Calculate the angles formed between parallel lines and a transversal. This free video geometry lesson will show you how. 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: Complete Fahrenheit to Celsius conversion

This video shows you how to convert temperatures from Fahrenheit(F) to Celsius(C). In the video, the example of 75 degrees F is used. The formula for converting Fahrenheit to Celsius is given by temperature in Celsius= (temperature in Fahrenheit- 32)/1.8. So for 75 degrees F we take 75 in place of temperature in Fahrenheit. Therefore the equation becomes (75-32)/1.8=C . Further 43/1.8=c and finally C= 24. Hence 75 degrees Fahrenheit= 24 degrees Celsius . This conversion is used as Celsius is ...

### How To: Calculate simple interest

Learn how to calculate simple interest with step-by-step instructions using the formula I=prt. Simply defined, interest equals principle times rate times time. The video shows various examples of calculating this formula by plugging different variables into the equation. Although, these calculations can seem hard to follow, the way they are presented is straightforward and simple to understand. The video also explains converting percentages to decimals, which is the cornerstone of applying th...

### How To: Subtract fractions from a whole number

In order to subtract fractions from whole numbers you have to perform a few steps. First we have to borrow one from the whole number. So if you are subtracting 1/16 from 3, 3 becomes 2. Then you have to change the one you borrowed, so the 1 becomes 16 over 16 or 16/16 to match the common denominator in the fraction 1/16. So 16/16 - 1/16 = 15/16. Then you add the 2 that you had left after you borrowed the one from the whole number. The answer is 3 - 1/16 = 2 15/16.

### How To: Simplify expressions involving algebraic radicals

In this video tutorial, viewers learn how to simplify expressions involving algebraic ratios. In some ways, simplifying algebraic radicals is easier than numeric radicals. When we are working with square roots, we need to find the highest even power of a variable to act as out perfect square. When working with cube roots, we look for the highest multiple of 3 as an exponent for our perfect square. This video is very descriptive and clearly explains all the functions of the formula. This video...