Transcript Decimals as Money

Lesson # 7
Decimals written as
money !
When doing operations with
decimals…
• Think about MONEY !
How much money is $0.05
a)
b)
c)
d)
5 cents
5 dollars
Half a cent
Or half a dollar ?
If you said…
$0.05 is …half a dollar…or half a cent…or 5
bucks……then…
I’m sorry…
• You are
• W
R
O
N
G
!!!!!!!!!!
$0.05 is equal to 5 cents.
Another example…
•
$0.025 is equal to…
A)
B)
C)
D)
A quarter
Two and a half cents
Twenty five cents
Two dollars and fifty cents.
If you said that $0.025 is equal to
B) Two and a half cents, then you are right!
So…
• When adding, subtracting, multiplying or
dividing …
• Numbers with DECIMALS….
Think about…
Cash
MONEY
An example of adding…
$0.015 + 0.015 = ?
$0.015 = one and a half cents
• Soooooooooo
0.015 + 0.015 equals…
• One and a half cents PLUS one and a half
cents…
• ( 0.03) Three Cents !
An example of subtracting…
• $1.25 – $0.05 = ?
Think…
• $1.25 equals one dollar and twenty five
cents…
• Subtract…
• $0.05 (a nickel)
• Therefore $1.25 - $0.05 = $1.2 (One dollar
and twenty cents)
An example of Multiplying…
0.12 x 2.0 = ?
Convert the “friendliest” number
into groups and the other to
MONEY!
0.12 x 2.0
• Make the 0.12 the money (12 cents)
• Make the 2.0 the number of groups
That means you have …
• Two groups of 12 cents…
• Which is 24 cents ( 0.24) !
An example of dividing…
• $0.35 ÷ 0.05 = ?
Think…
0.35 (35 cents) ÷ 0.05(5 cents)
How many times would…
• Five cents fit into 35 cents?
Seven ?
Right !
Lets get ready for 12 practice
questions !
•
•
•
•
•
12” ,
That’s right “
3 add,
3 subtract,
3 multiply and
3 divide.
Question # 1
0.1 + 0.01 = ?
Question # 2
0.25 – 0.2 = ?
Question # 3
0.5 x 3.0 = ?
Question # 4
0.35 ÷ 0.05 = ?
Question # 5
4.75 + 0.2 = ?
Question # 6
1.5 – 0.75 = ?
Question # 7
0.08 x 5.0 =
Question # 8
1.25 ÷ 0.25 = ?
Question # 9
0.025 + 0.25 = ?
Question # 10
1.1 – 0.03 = ?
Question # 11
25.0 x 0.01 = ?
Question # 12
2.25 ÷ 0.25 = ?
And now the answers…
• Get Ready!
Question # 1
0.1 + 0.01 =
0.11
Question # 2
0.25 – 0.2 =
0.05
Question # 3
0.5 x 3.0 =
1.5
Question # 4
0.35 ÷ 0.05 =
7
Question # 5
4.75 + 0.2 =
4.95
Question # 6
1.5 – 0.75 =
0.75
Question # 7
0.08 x 5.0 =
0.4
Question # 8
1.25 ÷ 0.25 =
5
Question # 9
0.025 + 0.25 =
0.275
Question # 10
1.1 – 0.03 =
1.07
Question # 11
25.0 x 0.01 =
0.25
Question # 12
2.25 ÷ 0.25 =
9
The
END !