You need to line up decimals for additional and subtraction. For multiplication, you don't need to line them up - in fact, it would serve no useful purpose.
line up the decimals together
When you are lining up decimals to add or subtract, always line the decimals up before doing the problem. An example is: 1.468 + 0.0004 would be lined up this way: 1.468 0.0004 1.4684 If this is a bit confusing, you could add a zero to 1.468 and it would be 1.4680. When doing subtraction, you would do the same. An example is: 4 - 0.086 4 can be written 4.0 or 4.000, so line then up like this: 4.000 -0.086 3.914
39.63 +42.35 ------------ 81.98 Just line up the decimals and then add.
line up the demials
You need to line up decimals for additional and subtraction. For multiplication, you don't need to line them up - in fact, it would serve no useful purpose.
line up the decimals together
no
When you are lining up decimals to add or subtract, always line the decimals up before doing the problem. An example is: 1.468 + 0.0004 would be lined up this way: 1.468 0.0004 1.4684 If this is a bit confusing, you could add a zero to 1.468 and it would be 1.4680. When doing subtraction, you would do the same. An example is: 4 - 0.086 4 can be written 4.0 or 4.000, so line then up like this: 4.000 -0.086 3.914
Just make sure you line up the decimals
Yes!
It is irrelevant if multiplying or dividing decimal numbers. For addition and subtraction it is not sufficient: you need to line up the decimal points as well as the digits according to their place values. If you intend to simply align the decimal points then you may as well not bother. This is to ensure that addition or subtraction is carried out for digits with the same place value.
-0.15
It is difficult to answer the question because, for addition or subtraction, it is often easier to obtain the exact answer! If you line up the decimal points and then follow the rules of addition or subtraction - exactly as they would apply to whole numbers - you will get the correct answer!Estimation may be useful to check your answer if you are poor at addition or subtraction of integers. But, if that is the case, your estimate is equally likely to be wrong!
39.63 +42.35 ------------ 81.98 Just line up the decimals and then add.
in a multiplication problem, you don't have to. in addition & subtraction, you do
No, it is not necessary. But it does help to be tidy.