How do you do add and subtract decimals?

Answer 1

How To Add/Subtract Decimals

1. To add decimals you HAVE TO LINE UP THE DECIMAL POINTS and then add the numbers up (Tip: when your first starting if the decimals don't go to the same place value you can add as may zeros at the END of the decimal. This does NOT change the place value)
2. After you have added up the digits you "drop" the decimal point down.

Example 105.43+23.4=?

105.43

+23.40

-----------

128.83

1. To subtract decimals it's the same thing as adding YOU MUST LINE UP THE DECIMALS. You would subtract as you normally would.
2. You would then "drop" down the decimal point.

Example 109.783-43.39=?

109.783

-43.390

----------

66.393

Answer 2

1) Write the numbers one above the other with the decimal points aligned;

2) Write the decimal point in the answer directly under the decimal points in the numbers;

3) Now add/subtract the two numbers "ignoring" the decimal points as if they were whole numbers, but if there is a blank in one of the numbers take it to be a zero.

eg 12.34 + 45.6:

12.34

45.6_+

-------

57.96

eg 12.3 + 5.64:

12.3_

_5.64 +

------

17.96

eg 57.2 - 2.34:

57.2_

_2.34 -

-------

54.86