Question 1

how did you get the decimals to line up with each other and why do you put a number off to the side

Accepted Answer

You line up the _decimal points_.

Wrong
```
  1.23
 +45.6
-------
 0.579
```
Correct
```
  1.23
+45.60
--------
 46.83
```

Question 2

how does this help us in a real life situation

Accepted Answer

You have to use decimals when go shopping. because if something cost 28.34 and then you also get another thing that costs 15.24 you have to add them so u know how much u spending

Question 3

how do you do it

Accepted Answer

★*Use the decimals to guide the place value alignment.

• line up the decimals above and below,
• _then add each column of numbers_,
• empty spaces are equal to zero*

9.087 + 15.31 = ?
```   9.087
+ 15.31
—————————
  24.397 ←🥳 answer```
★In *Addition* order doesn't matter, because it's *Commutative*, _meaning we can rearrange addition and get the same answer_, 
1 + 7 = 8
7 + 1 = 8
So *either decimal value can be first or second*, but _always line up the place values_.
```  15.31
+  9.087
—————————
  24.397 ←🥳 same answer```
★This method works for more than two values as well, as long as we _always line up the decimals so that the place values form columns_!

2.14 + 0.3421 + 3 + 11.2 = ?
```   2.14
   0.3421
   3
+ 11.2
——————————
  16.6821 ←🥳 answer```
Rearranged,
with place keeper zeros…
```  11.2000
   3.0000
   0.3421
+  2.1400
——————————
  16.6821 ←🥳 same answer```
★ Just remember: we *must _line up the decimals_ and keep the place values aligned* throughout the calculation, *move the decimal straight down, _so it is aligned in the answer too*_, then it's just adding the columns like usual…

Start adding in the far right column, carry values to the left, etc…

(ㆁωㆁ) Hope this helps someone!

Question 4

I made a chart and placed them into the chart to solve it, is that smart?

Accepted Answer

yes, it is very smart! i learned how to solve it using a chart, and it's good that you still use it as a strategy! ^^

Question 5

is it allowed to add an zero at the whole number?

Accepted Answer

I mean I get ur question. You can add a zero at a whole number. HOWEVER it won't change the answer. For example, 5+0=5. But it is allowed but no use.

Question 6

Do you align the decimals even if you are multiplying decimals

Accepted Answer

if you are multiplying decimals, you do not have to line up the decimal points. You keep the decimal points in the correct space in the numbers, but otherwise, write it out like a normal multiplication problem. You solve it like a normal problem too. so if it is 1.5 X 3.4, you would write it out like a normal multiplication problem:
  2
  3.4
 x1.5
--------
  1
  1 7 0
 +3 4 0
-------
 5  1 0, but to put in the decimal point, you have to think of the original numbers, which were 1.5, and 3.4, 1.5 had one number to the right of the decimal point, so note that, and 3.4 also had one number to the right of the decimal point, So note that as well, add that up and it means that you have to put the decimal point in the problem so that it is to the left of two numbers, so the answer is not 510, it is 5.10.

Question 7

The teacher made mistake because he didn't line up the decimals correctly

Accepted Answer

Sal failed to line up the decimals in the beginning on purpose to illustrate how operations cannot be carried out correctly if the decimal points are not lined up correctly.

Question 8

how to add 2.15 + 3.85+ 2.5 + .5

Accepted Answer

First make all the numbers have the same place value after the decimals by adding in zeros:
2.15
3.85
2.50 (is same as 2.5)
0.50 (is same as .5)
_____    
9.00

start by adding up the column on the far 
right and carry over to the next column to 
its left, then repeat.

6th grade

Course: 6th grade > Unit 2

Adding decimals: 9.087+15.31

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