Rounding & Estimating

Rounding: 
When it comes to rounding, it's really simple. If you were asked to round, go by these rules. 
1) If it's 5 and higher: round UP
2) If it's any number lower than 5: round down. 
For example, I chose the number 126. In this case, we're rounding it up to the nearest ten. Since it ends in a "6", we would have to go up. The number would now be 130.
If the number was 124, we would round it to 120 since 4 is lower than 5.

Estimating:
In some or most cases, estimating has to do with rounding. To estimate is to take a smart guess, but there has to be a reason.
For example:
- Adding: 126+163
     I could round 126 to 130 and I could round 163 to 160. So now the two numbers are 130 and 160.
     130+160= 190. 
     Now if you calculate the actual number, it would be 289. 

-Subtracting: 352-221
    I could round 352 to 350 and 222 to 220.
    350-220= 130
    Now if you calculate the actual number, it would be 131. 

In some cases, the two answers could be pretty close. 

Rounding and Estimating

Rounding- To round you need to take your number that your working with, so lets say I'm working with the number 63. If your number is 0 - 4 your going to round to a lower number, so if you want to round to your nearest tenth you look for the number after your tenths unit which is a 3, since 3 is under 4 your going to round down to 60. Say my number was 67, you're going to round up to 70, your going to do this because any number from 5 - 9, is going to be rounded up since these numbers are closer to the next tenth.


Estimating- To estimate, what I do is I round first. Lets say I want to add 56 and 32, to estimate this I round first. So, 56 rounded to the nearest tenth would be 60 because it's a greater number than 4, then we take the 32 and round it to the nearest tenth, which is 30. It's rounded to 30 because it's a lower number than 4. After you round your numbers you can add, subtract, multiply, etc. Now lets take the numbers we rounded, which is 60 and 30, add them together making 90. Since it's an estimation it is not going to be exact.

Estimating and Rounding

Rounding:

If you are estimating you have to ask yourself some questions. For example if you had the number 218 you can either choose to round to the nearest one, ten, or hundred since it's a three digit number. Now let's say you are rounding to the nearest ten, you look at the digit beside the tens place value which is 8. Now you ask yourself is 8 higher than 5? Or lower than 5? Or you can ask yourself is 8 closer to ten? Or closer to 1? Of course 8 is closer to ten so now the number 218 turns into 220.


Estimating:

Estimating, when you are estimating maybe for an assignment or a test it's almost the same concept with rounding. For example, if you have a question asking you, estimate the total cost of the T.V and the sofa. T.V costs $499.99 and the sofa costs $239.99. Let's round the cost of the T.V to the nearest hundred, now you look at the next digit beside the hundreds place which is 9, so is 9 closer to 10? Or closer to 1? 9 is closer to 10, so now $499.99 tunrs into $500. Now when you are estimating the cost of the sofa which is 239.99, it is pretty much the same concept, you look at the digit beside the hundreds place, which is 3, so is 3 closer to 10? Or closer to 1? 3 is closer to 1. Now, 239.99 turns into $200. After you are done rounding the prices you add them together. 500+200= $700.00 and that is your estimated answer. If you calculate the real price 499.99+239.99= $739.98, so this estimate is close to the real answer.

Estimating And Rounding

To estimate you would have to round to the nearest 1's, 100's, 1000's etc.

To know what number to round just round to the nearest numbers it says on the paper and once you figure that out then you have to look at the right (beside your number).

If your numbers are 5 to 9 the you would have to round it up, but if it is 1 to 4 then you would have to round down.

For example.....


Estimating with Decimals


Its just like the same thing but its just with decimals. But this time you have to round to the nearest tenth's, hundredth's, thousandth's etc.

You just have to remember 5 or higher your have to round up, but if its 4 and lower then round it down.

For example...

 

Over Estimating and Under Estimating

For over estimating that means you had to much of the right answer. For under estimating you got less of your answer.

For example.....