# Hot Math Posts

### How To: Perform short division

In this Education video tutorial you will learn how to perform short division. The first example is a division by a single digit; 741 divided by 3. You write it as shown in the video and start dividing from the left digit. So, 7 divided by 3 will give 2 with 1 as remainder. Write this down as demonstrated in the video. 1 and 4 make 14 and dividing 14 by3 will give 4 and remainder is 2. Now dividing 2 and 1, that is 21 by 3 you get 7. The answer is 247. The next example is 847 divided by 5. 8 ...

### 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: Find the formula in an arithmetical sequence

See how to find the formula for an arithmetical sequence in college-level algebra given two terms in this free video college-level 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 easier than ever to follow in their footsteps (or just finish your homework or study for that next big test).

### How To: Calculate percent yield

This video shows you how to calculate the percentage yield in chemistry. To find the percentage yield, you will need to divide the actual yield by the theoretical yield. Then, multiply it by 100: i.e. % yield = actual yield/theoretical yield x 100. An actual yield is the amount of a substance produced in an actual laboratory experiment. It is based on an actual physical measurement of a quantity. The theoretical yield is the yield as is calculated on paper: i.e. through calculations. Therefor...

### How To: Figure out a tip without a calculator

To figure out a tip without a calculator, first remove the pennies amount in the bill. For example, if your bill is $23.76 becomes $23.70. To figure out a 10% tip, move the decimal point one place to the left. So, 23.70 becomes 2.370 or $2.37. Bump up that number to $2.30 or $2.40 or $2.50 cents, depending on your preference. Since 20% equals two times 10%, double the figure you computed for 10%. So, $2.30 becomes $4.60, or $2.40 becomes $4.80 or $2.50 becomes $5.00. Using this method, you wo...

### How To: Multiply mixed numbers easily

This video tutorial shows you how to multiply mixed numbers. When doing this the first thing that you want to do is put the mixed numbers into a improper fraction form. From this step you can simplify the numbers based on what you are using. In this case you can take out the 3 and 21 and simplify it to 1 and 7 respectively. From here you do the basic multiplication to get one improper fraction. Then turn this number back into a mixed fraction to complete your problem.

### How To: Find the opposite and absolute value of a number

View the absolute value of a number as its distance from zero. When you take the absolute value of a number, you always end up with a positive number (or zero). Whether the input was positive or negative (or zero), the output is always positive (or zero). For instance, | 3 | = 3, and | _3 | = 3 also. This property that both the positive and the negative become positive makes solving absolute-value equations a little tricky. But once you learn the "trick", they're not so bad. Let's start with ...

### How To: Draw a rhombus from Geometry

In this video the author shows how to draw a rhombus when given with the values of long diagonal (D) and a short diagonal (d). Now he draws the long diagonal of size D horizontally on a sheet of paper. Now he points the mid point of the line as he explains that the diagonals of a rhombus meet at midpoints. So now he takes the ruler and draws an another line perpendicular to the first line through its marked mid point such that the length of the perpendicular line is d/2 both above and below t...

### How To: Draw a right trapezoid in Geometry

Watch this video to learn how to draw a right trapezoid using given specifications for lengths of sides. A right trapezoid is a four-sided shape with two right angles and two parallel sides. First, draw the long base. Then draw a 90 degree angle at one end of the base, using a protractor. Mark the angle to show it is 90 degrees. Then draw another 90 degree angle at the top. This is the first video in a set--to finish learning you must watch the next segment. If you watch these videos you will...

### How To: Plot a real number on a number line

This video tells you how to plot a real number on a number line. For example consider -3.1. You know -3.1 lies between -3 and -4. You also know -3.1 lies very close or next to 3. So all you have to do is, put a point just before -3. Now you have marked -3.1 on a number line. Similarly you can point any real number on a number line. It is quite an easy job to plot real numbers on a number line.

### How To: Analyze trigonometric functions graphically

Watch to learn how to use graphs to help analyze sine, cosine, and tangent functions in trigonometry.

### How To: Graph & shade a polygon of constraints

This video shows us how to graph & shade a polygon of constraints. Start out by finding the non zero constraints and the other constraints and inequalities. You will need to know how to graph before you begin to do this equation. Look at the first constraint and then fill in the X and Y sign in your table. Continue on to do this for the other two constraints that you have. Once you have these written down and in front of you, it's just a matter of graphing. Start to graph with the given coord...

### How To: Understand the properties of a rectangle

In this tutorial, we learn how to understand the properties of a rectangle. A rectangle has four interior angles that add up to 360 degrees. All of the angles have to be exactly 90 degrees in a perfect rectangle. Two opposite sides have to be congruent and parallel. The other opposite sides also have to be congruent and parallel. The diagonals of the rectangle are not perpendicular but they are congruent and they intersect at the mid points. Diagonals are not perpendicular, but they are congr...

### How To: Solve an absolute value equation and graph the answer on a number line

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 an absolute value problem in algebra and graph your answer on a number line.

### How To: Divide bigger numbers

In this video, we learn how to divide bigger numbers. As an example, let's say you were dividing 843 by 13. To make this easier, write down the times tables for 13 down and keep adding up. After you do this, see how many times 13 goes into 84. Your table will tell you how many times it goes into the larger number. Thirteen will go into 84 six times, so write six on the top line above the four, then subtract 78 from 84 and write a 6 next to the 4. Now, work out the remainder and when finished,...

### How To: Find percent by mass & percent composition

In chemistry you come across problems which ask you to find the percent by mass and percent composition of each element in a chemical compound. To do this the first step is to compute the molar mass. Use the periodic table to look up the mass of individual atoms and multiply it by the number of atoms to find the mass of that element. Now add up all the masses to arrive at the molar mass of the compound. Now to find the percent composition of an element divide the total mass of each element by...

### How To: Derive the area of a circle

This video is about deriving the area of a circle of radius 'r' using polar co-ordinate. First, we draw a circle and its radius 'r'. Then draw another radius close to it, so that it forms a small triangle-like figure. To find the area of the complete circle, divide the circle into similar small triangles. The area of each triangle is given by half the product of its perpendicular and the base. We give the angle between the two radii as d?. We get the area of the small triangle by substituting...

### How To: Find the slope of a line given 2 points

In this video the instructor shows how to find the slope of a line given two points that like on the line. Slope of a line is the measure of the steepness of the line compared to the angle made by the line with the x-axes. A line with positive slope slants forwards and a line with a negative slope slants backwards and a line parallel to x axes has zero slope. So if you are given two points (x1, y1) and (x2, y2), the slope of the line passing through those two points is equal to m = (y2 - y1)/...

### How To: Understand and work with rational & irrational numbers

In this video the instructor explains the concepts of rational and irrational numbers. Multiplying a number by itself gives the value of its square. If you apply the square root to that squared number it returns to you the original number. This square root is also called a radical. A square root of a positive number can have two values. For example the square root of 81 is either 9 or -9; this is because when you multiply 9 with itself the square is 81 and even when you multiply -9 with itsel...

### 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: Convert fractions to decimals quickly and easily

This video shows you how to easily convert a fraction to decimals. To convert a fraction to a decimal, you simply divide the numerator by the denominator. You first need to move the decimal point in the divisor to the right until it is a whole number. Then, you have to move the decimal point in the dividend to the right by the same number of places the decimal point was moved. Then divide the new dividend by the new divisor. Please note you may need to move the decimal point two places to the...

### How To: Find the area of a circle using squares

In this video the instructor shows how to calculate the area of a circle using squares. She starts with the formula of the circumference which she says is circumference C = Pi * D, where D is the diameter of the circle. Now she says that you can turn the shape of circle into a square and compute the area of the square there by calculating the area of the original circle. She shows how to do this by cutting up the square into sectors and arranging them in the form of a rough square and calcula...

### How To: Find the vertical asymptotes of rational functions

To find a vertical asymptote, you are trying to find values of x that produce 0 in the denominator but not in the numerator. If 0/0 occurs, that means you have a "hole" in the graph. A vertical asymptote is a place in the graph of infinite discontinuity, where the graph spikes off to positive or negative infinity. To find the vertical asymptote, set the denominator equal to zero and solve for x. Check that the values also do not give a zero in the nominator. If the values work, you have found...

### How To: Convert improper fractions to mixed numbers quickly

Watch this video to learn how to convert improper fractions to mixed numbers. For example, follow these steps. First step is one fraction value. For example 7/3. Second step is divide the numerator by denominator means when 7 divide 3 you can get remainder as 1. Means 7 before value can multiply with the 6 so you can subtract 7-6=1 that is remainder. Multiplied value of 3 nothing but 2 is multiplication of the mixed numbers remainder take it as a numerator and denominator is always take it as...

### How To: Calculate and solve for density

Density is a means of representing how much mass is contained in the body of an object. The basic formula is: Density (D) = Mass (M) / Volume (V) so D=M/V. Density is important to know for buoyancy and to understand how heavy an object is. This video will show you three examples of measuring density so you can learn and put it to good use.

### How To: Divide variables

This is a helpful video provided by Math Problem Generator. It deals with the complex challenges of dividing variables. The audio is great and provides specific examples of dealing with multiple types of this problem. The video lays out three simple steps. The first being to simplify the coefficient, the second being to divide the variable, and the third being to deal with the results of the division. The information is clearly presented and best of all it's free. I think we all wish there we...

### How To: Find the surface area of a surface revolution

From the people who brought you the Dummies instructional book series, brings you the same non-intimidating guides in video form. This is Mathematics for Dummies. Just watch this video tutorial to learn how to find the surface area of a surface revolution, For Dummies.

### How To: Construct 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 construct intervals with a TI-83 graphing calculator.

### How To: Subtract fractions and mixed numbers

See how to subtract fractions. Turn those mixed numbers into improper fractions to solve. Improve your math skills!

### 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: Calculate a limit at infinity with a radical

In this video, we learn how to calculate a limit at infinity with a radical. The idea is to take out the higher power of 'x' in the denominator first. If the x squared is under a radical, take that out so you're left with just 'x'. After this, divide every term by 'x'. Once you are finished with this, you can rewrite the equation. Next, you will use the rules of math to find the answer of the equation. This is hard math to do if you aren't used to it! Make sure you practice with the samples i...

### How To: Calculate the surface area of a rectangular solid in basic geometry

With mathematics, as with anything else, not everyone progresses at the same rate. Geometry 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. With this free video math lesson, you'll learn how to calculate the surface area of a rectangular solid.

### 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: Solve a geometric series or sequence

See how to solve a geometric series with this free video geometer's 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 (or just finish your homework or study for that next big test).

### How To: Use the upside-down birthday cake method to find a GCF

Need to find the greatest common factor for a set of numbers? Easy as cake. Learn how to find GCFs using the upside-down birthday cake method 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: Write rational expressions in lowest terms

In arithmetic, the simplest expression is far preferred to the long eye-boggling one. Stop making your expressions painful optical illusions by watching this tutorial on how to write rational expressions in the lowest terms.

### How To: Plot absolute values on a number line

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 plot absolute values on a number line in simple algebra/geometry.

### How To: Divide decimal numbers by whole numbers in basic math

Your first step is to bring your decimal point up to the top of the equation. The you divide the whole number into the decimal number. In this instance, 5 into 1.25. 5 goes into 1 0 times, so you put the zero in the first space. 5 goes into 12 twice, so you place a 2 up top, after the decimal. Then you subtract 10 from the 12 to leave you with a 2. This then gets added on to the 5, so you divide 2 into 25 giving you 5. So your answer is 0.15. You can then do this for any whole number and frac...

### How To: Prove an inscribed angle is half of a central angle

This video walks you through the steps to prove an inscribed angle is half of a central angle that subtends the same arc. This excellent video shows you a clean blackboard, with the instructors voice showing exactly what to do. Don't fret, any question you may have, will be answered. Watching this video will make you feel like your back in the classroom but rather comfortably from your home.

### 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...