Adding and Subtracting Decimals

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Adding and Subtracting Decimals

• Frank Wang

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What and When do you Need to?

• When do you need to add and subtract decimals?
  The most common use of adding and subtracting
  decimals is money. Some other things that you
  will need to add and subtract is measuring, or
  just plain old math.

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Decimal Place Value

• First, to add and subtract decimals, you will
  probably need to know the place values. The order
  is

TENTHS
The trick is that every decimal place value is a
normal place value but with a ths at the end.
HUNDREDTHS
THOUSANDTHS
TEN THOUSANDTHS
HUNDRED THOUSANDTHS
MILLIONTHS
You can consider the decimal point a mirror,
just with a ths at the end of every reflection.
(It goes on and on and on.)
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Decimal Place Value

• What place values are these underlined decimals
  in?
• 0.74348 1.4675
• 0.38593
  0.78439275943
• 0.734892075489302754903754893725840

_
_-
_ _
_
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Then What??

• After you get the place values of the decimals
  correct, get the question and line up the place
  values. So, 15.923 28.78 becomes
• 15.923
• 28.780

The 0 is a placeholder so it lines up. Still,
28.7828.780.
___________
Its like normal numbers but on the right end
98098 and so 28.7828.780.
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Solve!

• Add or subtract normally. Drop the decimal point.
• 15.923
• 28.780

1
1
1
__________
3
0
7
4.
4
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Subtract!

• Same thing with subtraction. Follow the work
  shown.

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Try it Out!

• Try this question to see if you learned how to do
  decimal addition correctly.
• 64.759 74.76 ?????

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The Answer Is

• 139.519!!!!
• Nice job if you got it right!! If you didnt, try
  again.
• If you still got it wrong, follow the work.

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Try it Out!

• Try out this question to see if you learned how
  to subtract decimals.
• 97.547 64.36 ?????

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The Answer is

• 33.187!!!!
• Nice job if you got it right!! If you didnt, try
  again.
• If you still got it wrong, follow the work.

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Review

• What are the place values of decimals?
• How do you solve a decimal problem?
• When does decimal addition and subtraction come
  in handy?

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Wooooo!!

• Congratulations! You have fully learned how to
  add and subtract decimals correctly.
• YAAAAAAAAAAAAAAAAY!!!!!!

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Credits

• PowerPoint by Frank Wang
• Information from THE WORLD
• Typing by Frank Wang
• Wording by Frank Wang
• Contributors YOU!!!!!
• Almost everything else by Frank Wang