Because 42.0+7.8 is different from adding 42+78. it makes adding easier!
explain why it is important to line up decimal numbers by their place value when you add or subtract them
This is true for adding and subtracting ALL numbers, not just decimal representations.
That is because if you don't, you will get the wrong answer. It is ALWAYS important to LINE up the decimals.
Line up the decimal numbers like this, 100.5 + 9.0 then add normally and put in the decimal right below the decimal obove.^
line up the numbers and decimals multiply regularly then bring the decimal down
Because if you don't line them up you will get a total different answer.
We line up the decimal numbers so as to get accurate results. Example: 0.2 + 7.31 + 1.054 * It is easier to add this vertically. 0.2 7.31 1.054 ==== 8.564
It is easier to add up numbers. It may also be easier to spot errors where the decimal point is misplaced.
No, it is not true.
To add decimal numbers you line up the decimal points... _0.88 +0.035 --------- _0.915
So the decimal points line up and you can have a visual clue that larger numbers are longer.
Because the number of digits after the decimal place in a product does not require that.