Question

Why is it important to line up the digits in each place value position when subtracting?

Answer 1

so that you don't subtract the wrong numbers and get the wrong answers. ,
123
-----
386
_____
?

Answer 2

It would not make sense if you were to do
34
28
The right way is

34
28

Another example is that if you were to subtract by 1 digit by 2

78
1

This is the wrong one

78
1