Question

Why is it important to line up decimal numbers by their place value when you add or subtract them

Answer 1

So that you don't add the whole number to the the decimal by accident... For example: .04+ 1.0 = 1.04 but if you didn't line up the decimals and you only lined up the numbers you would have .14

Answer 2

So that you dont add up the whole number to the decimal part