Addition, Subtraction, Multiplication, and Division


Addition, Subtraction, Multiplication, and Division
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Addition, Subtraction, Multiplication, and Division


These are the four basic operations that we work with. Addition and subtraction are opposites of each other. With addition we increase a number by another number. For instance, if we were to add 4 plus 2, we increased 4 by 2 to get the number 6.


We could also do 8 plus 9. We can increase 8 by 9 to get 17. With addition the order that you add numbers in, doesn’t matter. 4 plus 2 is 6 but also, 2 plus 4 is 6. We can do the same thing with 8 plus 9. 8 plus 9 is 17, but also 9 plus 8 is 17.


It doesn’t matter the order that you add two numbers together, you’ll get the same sum. That’s what that number is called. 17 is a sum, it’s the result of adding our 2 numbers together, 9 and 8. Subtraction, like I said, is the opposite of addition, because you’re decreasing a number by another number.


For instance, if we did 5 minus 2, then we’re decreasing 5 by 2 to have the result of 3. This is called the difference. 3 is the difference between these numbers 5 and 2. With subtraction, the order does matter because 2 minus 5 would not also give us 3.


It would give us -3, because we took away more than we had. Which means we’re now in the negative. Order matters with subtraction, but it does not matter with addition. Multiplication and division are opposites of each other. One, you increase the numbers.


In the other the numbers are decreased, or a number is decreased. Multiplication can also be thought of as repeated addition. For instance, 3 times 2 means to add 3 to itself 2 times which will give you 6. 2 times 3 means to add 2 to itself 3 times, which still yields 6.


This is called the product. As you can see with multiplication, again, the order that the numbers are multiplied in doesn’t matter. 3 times 2, and 2 times 3 both yield 6. With division we decrease a number, like 20 divided by 4.


What we’re doing is taking 20 items and dividing them evenly into 4 groups. What we want to know is, how many items would be in each one of those groups. The answer is 5. If we took 20 items and split them up evenly into 4 different groups, then there would be 5 items in each group.


With division, order definitely matters. 4 divided by 20, is not also going to give us 5. It’s actually going to give us 1/5. If you had 4 dollars, and you’ve split it up between 20 friends, they’re each only going to get 1/5 of a dollar.


Not even one whole dollar. With addition and multiplication, order doesn’t matter. You can add or you can multiply in any order and get the same result. With subtraction and division, order definitely matters. You’ll get a different result depending on the order you subtract or divide the numbers.



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Last updated: 10/03/2018

 

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