Subtracting Decimals and Whole Numbers

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Subtracting Decimalsand Whole Numbers

• Lessons 1-7

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Subtraction

• Lets go back to the bank first

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THE BANK of MOM
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THE BANK of MOM
I dont have enough money! Who can I ask to help
me out?
Sure, Honey. This 10 should be enough even if
it means I cant eat tomorrow because you took my
last oneltsniffgt
MOM?
If you dont have enough money to pay your debts,
then turn to the person to your left and keep
working your way on down the line asking each
person until someone has some money to lend you!
If you had to go further than one place, you need
to make change with each person on your way back,
too.
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HoweverSometimes life just isnt that easy!
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THE BANK of MOM
I dont have enough money! Who can I ask to help
me out?
I dont have any. Go ask your father.
What do I look like? A bank? Go ask your
grandmother!
MOM?
DAD?
No problem, Honey. Here you go. Dont forget to
give some to your dad and mom before you go and
spend it all!
GRANDMA?
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Rules for borrowing money from
THE BANK of MOM
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In subtraction, we only work with money that has
zeroes and ones in it--NO quarters, nickels, or
five dollar bills are allowed!
Thats right! No two dollar billsno twenties no
fifties either
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THE BANK of MOM rules

• When you subtract, there will be times when you
  do not have enough money. Too bad! You must pay
  your debts!
• If this is the case, then you HAVE TO borrow the
  money. If you owe money, then you have to pay
  money.
• If you ask the person to your left to lend you
  some, then they HAVE TO help you if they have at
  least 1 piece of money

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• Every one dollar or coin you take away turns into
  10 of a different dollar or coin when it you get
  it.

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Borrowing in Subtraction
Thank you, Dimes, for giving me ten pennies.
Sorry you have one less dime though
1 dime 10 pennies
,
10
penny
dime
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Change 1 dime into 10 pennies
Look at all those coins I borrowed
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I wonder if anyone noticed my new hair style?
Borrowing money has sure made it easier for me to
take care of myself!
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Borrowing in Subtraction
Thank you, Dollars, for giving me ten dimes. So
sorry you have one less dollar, though
1 dollar 10 dimes
,
10
dime
dollar
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Change 1 dollar into ten dimes
Hoo Hee! Ten dimes are mine just because I asked
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Borrowing in Subtraction
A ten-dollar bill 10 one-dollar bills
Thank you, Tens, for giving me ten dollars. Sorry
you have one less though
10
,
dollar
ten dollars
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Change 1 ten-dollar bill into 10 one-dollar bills
Thank you, Tens, for giving me ten One-dollar
bills. Sorry you have one less though
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Borrowing in Subtraction
1 hundred-dollar bill 10 ten-dollar bills
Alright! I just LOVE that everyone gives me
money simply because I asked
10
,
Hundred dollars
ten dollars
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Borrowing in Subtraction
1 thousand-dollar bill 10 hundred dollar bills
Yep, yep, yep! Keep it coming! Money! Money!
Money!
10
,
hundred dollars
thousand dollars
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Here is how subtraction works
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Solving the problem

• Put the first number on the top
• Put the second number on the bottom
• Line up the decimal points and all your place
  values
• Put the operation sign next to the bottom number
• Fill in each empty place value with a zero
• Subtract each column
• If you try to BORROW money from the top number
  and there isnt enough, then you have to go
  begging for money from mom, and maybe dad, and
  possibly even grandma.
• If you go past the first person on your left, you
  have to give everyone money along the way back to
  your place.

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22.9 - 3.36 ____
first
second
Mom gave me her dimeso she has one less dime. I
changed the dime she gave me into 10 pennies. Now
I have 10 0 pennies 10
-
22.9
3.36
12 3 9
The 9 is crossed off. I need to subtract from
the 8 now. 8 3 5
1 0 1
I only have 2, but need to pay back 3. I MUST
borrow! 10 2 12
You need 6 pennies, but I dont have any. I need
to borrow from The Bank of Mom.
22.9
8
10
1
12
0
What I have
3.36
0
-
19.54
.
What I need to pay
10 6 4
5
1
9
4
What I have left
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229 4.35 ____
first
second
Mom didnt have any money. She sent me to go ask
Dad. He gave me a dollars worth of dimes. So now
he only has 8 dollars. I gave the dimes to Mom
and she gave me a dimes worth of pennies, so now
she has 9 dimes. Finally, I have 10 0 pennies
10
-
4.35
229
The 9 is crossed off. I need to subtract from
the 8 now. 8 4 4
Notice that there is NO decimal point! This is a
whole number. There is an imaginary decimal point
at the end!
You need 5 pennies, but I dont have any. I need
to borrow from The Bank of Mom.
.00
8
9
10
10
229
What I have
4.35
9 - 3 6
2 0 2
0
0
-
224.65
.
- What you need
10 5 5
2
4
6
5
2
What I have left
2 0 2
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Lets Practice
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14.67 - 1.01 _____
14.67
- 01.01
13.66
3
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23.9 - 14.67 _____
10 plus the 3 that were already here make 13.
8
1
13
10
23.90
- 14.67
9.23
2
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9 - 8.63 _____
9
10
10
8
9.00
- 8.63
0.37
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