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How to Add, Subtract, Multiply, & Divide Decimals
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Adding Decimals
1. Rewrite the problem vertically with the PLACE VALUES LINED UP.
2. If you need to, fill in empty spaces to the RIGHT of the decimal with zeros.
3. Add the numbers together – you may add the addends in any order.
4. You can add together as many numbers as you want at one time.
5. Place the decimal in your sum between the same place values it came from.
Addition Example
12.347 + 9.62 =
12.347
+ 9.620
21.967
CHECK WORK:
Subtract one addend from the sum and you should get the other addend.
21.967
- 9.620
12.347
Subtracting Decimals
1. Rewrite the problem vertically with the PLACE VALUES LINED UP.
2. If you need to, fill in empty spaces to the RIGHT of the decimal with zeros.
3. Subtract the numbers –DO NOT CHANGE THE ORDER!
4. You can only subtract two numbers at a time!
5. Place the decimal in your difference between the same place values it came from.
Subtraction Example
12.347 – 9.62 =
12.347
- 9.620
2.727
CHECK WORK:
Add the difference (the answer) to the number you subtracted and you should get the original
number.
9.620
+2.727
12.347
Multiplying Decimals
1. Rewrite the problem vertically. You do NOT NEED TO LINE UP THE PLACE
VALUES!
2. Multiply the factors.
3. Count the total number of decimal places in the factors to the RIGHT OF THE
DECIMALS.
4. Starting on the farthest right of your product, count moving left the same number of
decimals that you counted in step 3.
5. Place the decimal where you stop counting. Zero fill to the left if you need to place the
decimal point farther to the left than you have digits.
Multiplying Example:
12.347 * 9.62 =
12.347 (3 decimal places to the right of the decimal)
x 9.62 (2 decimal places to the right of the decimal)
24694
740820
11112300
118.77814 (5 decimal places = 2 + 3 from factors above)
CHECK WORK:
Divide the product (answer) by one of the factors and the quotient will be the other factor.
118.77814 ÷ 9.62 = 12.347
Dividing Decimals
1. Rewrite the problem with the divisor on the outside of the “house” and the dividend on the
inside of the “house”.
2. If the divisor has digits to the right of the decimal, move the decimal right to the very end
of the divisor.
3. Move the decimal in the dividend to the right the same number of places.
4. Move the decimal up to the top of the “house”.
5. Divide
Division Example
118.77814 ÷ 9.62 =
9.62 118.77814 - move the decimal in 9.62 two places to the right and make that number 962
12.347
962. 11877.814 and move the decimal in 118.77814 two places to the right – 11877.814
 CHECK WORK:
Multiply the quotient (the answer) by the divisor and you will get the dividend.
12.347 * 9.62 = 118.77814
