Percentage

Hi,
Today we are going to talk about percentage.Percentage is a fraction of something out of 100.For example if you look at your grades on school grade book, 80% means, you have 80 points out of 100. Let us see how we can use this simple math fraction in science.We all can not survive with out water.We know that  75% of earth is water that means 75% of earths surface is covered with water.Water is made up of elements hydrogen and oxygen.The chemical formula of water is H2O. Let us see if we can calculate the percentage of oxygen in water.Water has a formula mass of 18.The atomic mass of hydrogen is 1 and the oxygen is 16.So for H2O,the mass will be 2x1+16=18.
     Let us see how we can calculate the percentage of oxygen in water.If we have 16 for every 18 of water then how much w e have in 100?
16/18 = A/100
16 x 100 = 18 x A 
Dividing both sides by 18 will give you 
A=(16 x 100)/18
The answer is 88.88%.
In this way you can calculate the percentage of any component in any compound or material.This simple math is used every day by people like engineers, chemists,etc...

subtracting integers

                 





Hi,
Today we are going to talk about subtracting integers.When you are subtracting integers you have to make sure you do it correct.you have to add both the negitive numbers and put a negitve sign in front.


lets do some exsamples.-3-12.First we do 3+12 and get 15.Because it is a negative we put a negive sign in front.It is very easy.

adding intergers

 

                adding integers

Hi,

Today we are going to learn how to add integers.Adding integers is kind of tricky and confusing but I will show you how to do it.Adding integers means that you have to do problems like -9+8=?.The answer to that would be -1.When adding you must go up, but when you adding integers you must go down and then up.When you count negative numbers you count 5,4,3,2,1,0,-1,2,-3,-4,-5 and so on.See that you count up on negative numbers even though you are going down. So when you are adding you go down and then up. Do you get it?Answer on the side bar pool.

Lets do some examples.-5+9=?.So first we count down 9.-4,-3,-2,-1,0.Now we go up,But first we have to find out how many we have counted so far.We have counted 5.Now we count up 4.1,2,3,4.The answer is four.

multiplying integers

                                  Integers

Hi,

Today we are going to talk about integers. Integers are numbers that are positive and negative.  Multiplying them is just the same as multiplying regular numbers. Here is a chart that can help you.

  

p	n	n
n	p	n
n	n	p

key:  p= positive  n= negative

In this table, you read from right to left, downwards, or diagonal. So lets look at the first row across.

p x n =n 

The first column downwards is a similar math operation.

p x n = n

Going diagonal  

p x p = p

The bottom row 

n x n = p

The rest, if you go in any direction, will be one of the above operation.

Lets do an example.9(-11). First lets see if the answer is positive or negative. So the problem on the table would be,p x n =n. So the answer is negative. Now it is simple multiplication. 9 x 11=99. So the answer is -99.

mode

 

                                           mode

Hi,
Today we are going to talk about mode. The definition of mode is the most occurred number in a set of numbers. If two numbers occur the same number of times then there is no mode. Like if I had the numbers 5/5/5/5/8/8/8/8/2/4/9/6/4/3.There is no mode. there is four 5s and four 8sThat is mode



lets take the problem 5/4/6/7/8/9/1/2/3/5/4/6/5/4.There are one 1/2/3/7/8/9.two 6s and there are three 4s and 5s.The most occurred numbers would be 4 and 5. We can not have 2 modes so there is no mode. thank you.


tip, an easy way to remember mode is most occurred decimal in equation.

median

                                  median

Hi,

  Today we are going to talk about median.The definition of median is the middle value when the values are written in numerical order.If a data set has an even number of values,the median is the mean of the two middle values.we will be doing some practice next paragraph.That is what median is.


lets do the problem 23,24,25,27,28,19,30.first we put the numbers in order.19,23,24,25,27,28,30.Then we find the middle.25.That is how you find median.thank you.

mean

Hi,
 Today we are going to talk about mean.Mean is when you add a bunch of numbers and divied by how many numbers there are in toal. The numbers can be any like 1/2,52148863457.55255416,or 64545155/535841518556.

Lets take the numbers 78,32,65,25,458,232.
To find the mean You would add them up and divid When you add them you will get890add if you divid them by how many there are (6)you will get about 148.That is how to find the mean

Pemdas

         

                                            pemdas                            

                                                       pemdas

Hi,                                                      

 I am going to talk about PEMDAS. PEMDAS is a mathematical order in witch you preform math operations. For example, the order you preform when you have a question like 9² +(18+2)-(12+876).
PEMDAS means P-parenthies, E-exponents, M-multiplcation, D-divition, A-addition,and S-subtraction. PEMDAS is to be done in that order.That is why it is called order of operations.Always go left to right when doing it.


                                                          answer                                                                                                                                    


lets say we want to solve 9²(18-16)÷(11+1). So first we go in order of PEMDAS.So we start with parentasece in 9²(18-16)÷(11+1).18-16=2 and 11+1=12. Now the problem is 9²(2)÷(12).next is exponets.9x9=81. now it is 81(2)÷(12).Next we do multiplcation 81x2=162. Now the question is 162÷ 12 and now we do divtion. The answer is 13.5.If there was more you would do addition then subtraction.