# Hot Math Posts

### How To: Use a protractor to make a pie chart

If you have a circular or semicircular protractor like the one used in this video, making a pie chart is as easy as â€“ well â€” pie. This will teach you how to use your protractor to measure out each individual slice in your pie chart. Learn how to visualize statistical data through hand-drawn pie charts with this free video math lesson.

### How To: Understand the central limit theorem

Central limit theorum is easily one of the most fundamental and profound concepts in statistics and perhaps in mathematics as a whole. In probability theory, the central limit theorum (CLT) states conditions under which the mean of a suffiently large number of independent random large variables (each with finite means and variance) will be normally distributed, approximately. Huh? If you are having trouble understanding central limit theorum and need help trying to solve it, check out this tu...

### How To: Calculate percent error

For all you high school students trying to understand physics, this tutorial is here to help show you how to calculate the percent error. This may seem like a very hard problem to solve, and it can be, but in fact can be easy to solve with the right help. So this tutorial is here to give you the information that you may or may not know. So good luck and enjoy!

### How To: Solve linear equations in matrix form (Ax = B)

Need to know how to solve a matrix-form linear equation in 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 solving lin...

### How To: Factor perfect square polynomials

Learn how to factor perfect square polynomials and how to solve equations using the square root property. 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: Draw an isosceles trapezoid

This is a video tutorial in the Education category where you are going to learn how to draw an isosceles trapezoid. This video demonstrates how to draw an isosceles trapezoid with a long base (B), a short base (b) and a 35 degree angle. First you draw the long base. Now center the short base at the center point of the long base and mark the end points of the short base with dots. Next draw perpendicular dotted lines from the dots extending upwards. Draw 35 degree angles from either end of the...

### How To: Factor trinomials with the "bottoms up" method

After an easy way to factor trinomials in algebra? Try the bottoms up method! 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: Do long division problems

In this tutorial the instructor shows how to perform a long division through an example. He gives a simple method where takes the first left most number, with minimum possible digits that can be divided by the divisor, and tries to divide it by the divisor and this gives the quotient. Now he shows how to multiply the quotient with the divisor to get a value which is to be subtracted from the original divided number. Now in the third step he shows how to bring down the next digits and asks to ...

### How To: Solve quadratic inequalities in calculus

Calculus can be a bit tricky, but don't worry, Watch Math is here to help you out. Watch this math video lesson to learn how to solve quadratic inequalities in calculus. There's no better way to learn mathematics than from an advanced mathematician, like this PhD.

### 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...

### How To: Compute mathematical problems in your head

This educational video tutorial will show you how to compute mathematical problems in your head. You will see some techniques to do some maths problems in your mind. Learn to do algebraic computations in the head without having to look at a calculator. Become a human calculator!

### How To: Solve linear equations in the form of AX+B=C

Need to know how to solve AX+B=C-form linear equations in 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 solving line...

### 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: Find a number given Its percent

This how-to video is about how to find a number when its percent is given. This video is really helpful and effective in finding the number when the percent is given, the following steps are explained in the video to find the number when its percent is given:

### How To: Write a slope-intercept equation given an X-Y table

In this tutorial the author shows how to derive a slope-intercept equation of a line given an X-Y table. He explains that the general form of slope intercept form which is y = m*x + b. Now he intends to find value of slope, i.e. m first. Now slope is change in y over change in x. He computes the slope using the X-Y values from the table. Next he substitutes a pair of x, y value in the equation to compute the value of y intercept b. Now finally substituting the values in the equation the slop-...

### How To: Learn Calculus in 20 minutes

Did you sleep all semester in your Calculus class? Are you just waking up now to realize you have a test on Monday and that you're totally screwed? Well, luckily you can learn an entire semester worth of Calculus in just twenty minutes... or at leasts that's the hope.

### How To: Find the Slope Given 2 Ordered Pairs

Slope is the change in Y over the change in X. Written out, the formula looks is as follows: (y2-y1)

### How To: Complete a proof involving segments

This video from Yay Math! is a geometry lesson on how to complete a proof involving segments. He draws a line segment with four points labeled A, B, C and D. The problem is as follows: Given: AC is equivalent to BD. Prove that AB is equivalent to CD. The first statement of proof is the given. Next, you need to define the congruent segments and state that they're equal in measurement. Next, break down the segments: AC=AB+BC, and BD=BC+CD. This is called segment addition postulate. The end of t...

### How To: Find a slope of a straight line with: Ax + By + C = 0

In this video the instructor shows how to find the slope of an equation which is in the form Ax + By + C = 0. He says that the formula to find the slope of a line in the above form is slope m = -A/B, where A and B are the numeric constants of the variables x and y in the given equation. He goes on and further shows how to do this with a couple of examples. He shows how to reduce any equation into the general form and how to apply the slope formula then. This video shows how to find the slope ...

### How To: Solve for the missing ratios or proportions

In this video the tutor shows how to solve the missing ratios or proportions. He explains it with an example, where a number in one of the ratios is missing and he intends to find this value. He shows the example of cross multiplication, where you multiply the values on the either side of the equation diagonally and finally solves the equation which results in the value of the unknown value. This is an introductory video explaining how to use rations and proportions to find missing values.

### How To: Convert Fahrenheit to Celsius with a formula

In order to convert Celsius to Fahrenheit, you will need to use this formula: F = 9/5C + 32. Therefore, you will need to solve for C or substitute values and solve in that manner.

### 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: Translate a shape

Learn how to translate shapes with a few simple steps. - First step: Find the new verticals under the transformation which are T3,2. Values are A=(-5,-8), B=(-3,-4), C=(-8,-3), D=(-6,1). Find the points of the verticals on the graph and connect the points one by one until you can get one shape.

### How To: Calculate math without a calculator

Before the calculator and even the abacus was invented, there was a little instrument called the human brain that we used to do math. Remember that? While most of us turn to our trusty Ti-84s to do calculus homework or whip out our cell phone calculators to determine how much we should tip at Johnny Rocket's, it can often be much faster to use our own brains, along with a piece of paper and pencil.

### How To: Multiply & Divide Numbers (Basic Elementary Math)

Adding and subtracting may be the easiest of mathematical operations, but once you get it down, multiplication and division can be just as easy. That's why it's called elementary arithmetic. If it were harder, it would be called college algebra or trigonometry. But it's notâ€” it's basic math, and once you get your head around the numbers, you'll never hate math class again! (Okay, maybe you will.)

### How To: Factor a trinomial with negative leading coefficient

In this video the instructor shows how to factor a trinomial with negative leading coefficient. Most of the students are confused when they have to factor a trinomial with a negative leading coefficient. But there are many ways to solve these kind of problems as shown in this video. One way you can do is that take out the greatest common factor (GCF) of -1 from the equation. So pulling the -1 gives you the original trinomial with all the signs of the terms changed. Now go on and factor the ne...

### How To: Do long division with decimals

Video Nerd thinks that when your doing long division with decimals you should first take out the decimal. Write the number as if it didn't have a decimal. For example if the problem was 12.5 divided by 5 then you will just use 125 and divide that by 5. Next divide the first digit of the dividend by the divisor an write the number up top. Next you multiply, after your done multiplying the numbers subtract, and when your done subtracting the numbers drop the reaming numbers in the dividend down...

### How To: Normalize a data set into another scale

Comparing evaluations of the same thing done on different scales can seem difficult, but there is a simple equation you can use to translate something expressed in one numerical scale into another. This video will show you how to use it and make your math life easier.

### How To: Do a rotation in Geometry

Learn how to do a rotation in geometry with this video! First step is to pout the pencil into the compass. Adjusting the pencil and compass needle is same. Suppose you want 165 degree size circle. Measure the reading with compass in protractor. Note the point and adjust the compass. After place the sharp end of the compass at the point and rotate the compass the circle will enabled. Next use protractor. We see 75 degree acute angle. Place the protractor on the line and mark the reading we wan...

### How To: Express a ratio as a fraction in simplest form

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 rewrite a ratio as a fraction in its simplest form.

### How To: Find density using the water displacement method

To find out the density of any given object there is a simple equation, mass divided by the volume equals the density. In this video a lady is showing how to get the volume of three objects using water. First the objects are measured on a scale to find out how much they weigh, the mass. Next each one of the objects is placed into a measured amount of water to find out the volume. Before you place the object into the water you will want to know just how much water in there. That way when the o...

### How To: Find the equation of a line given 1 point

Need help figuring out how to find the equation of a line given a single point? 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: Evaluate square roots

This is the video about how to evaluate square roots. The square root of a number is a number that you can square to get it, that is, a number that you can multiply by itself to get the number. So, 2 is a square root of 4, because 2 x 2 = 4, and 3 is a square root of 9, because 3 x 2 = 9. (-2) x 2 is also 4 and (-3) x 2 is also 9. Numbers that have square roots always have two, a positive one and a negative one, but the square root symbol means only the positive one, so we can have one answer...

### How To: Write a fraction as a decimal

Write a fraction as a decimal

### How To: Clear fractions from linear equations in Algebra

Need help figuring out how to remove fractions from linear equations in algebra? 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: Find the equation for a growth pattern

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 an equation that describse the growth pattern of a sequence of blocks.

### How To: Be a human calculator

Before we had the calculator and before we had the abacus we had the human brain to complete our math problems for us. Remember that? Well, it seems that few of us do, resorting to calculators on our phone for elementary subtraction problems and multiplication.

### How To: Solve direct proportions

You can solve any proportion using the fundamental rule of proportions. First you must build the proportion if you are given a word problem. Decide using logic whether it is a direct proportion (more on one side means more on the other). If so, find the parts of the equation that use the same units and make a fraction with these, putting the smaller number on top. The number left over is linked with one of the other two numbers in the fraction--use logic to figure out which. Put it in the sam...

### How To: Divide larger numbers and do long division

This is video for how to divide large numbers by doing long division with easy methods. This video describes that dividing the "Dividend" with "Divisor" to get the "Quotient" and "Remainder" if they exist. In the given example first "25" taken as the Dividend and "5" is will be the Divisor. Divide this value the multiplication is needed. For above example "5*5=25" is the result so, the "Quotient" is "5".If the value is large for example "506" of dividend and "8" of divisor means, first we sho...

### How To: Derive the equation of a straight line

In this tutorial the instructor shows how to derive a straight line equation. He shows us a process that consists of two steps. In step one he uses the slope formula to obtain the slope of the line which is the ratio of difference of y-coordinates and difference of x-coordinates. Now in the step two he uses the slope he obtained in the first step and equates it two a another slope derivation which uses a generic x, y variables and a real point. Now solving this equation he arrives at the equa...