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Learn how to perform operations with decimals using money as examples. Understand that decimals represent cents. Practice adding, subtracting, multiplying, and dividing decimals through 12 practice questions.
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Lesson # 7 Decimals written as money !
When doing operations with decimals… • Think about MONEY !
How much money is $0.05 a) 5 cents b) 5 dollars c) Half a cent d) 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 !!!!!!!!!!
Another example… • $0.025 is equal to… A) A quarter B) Two and a half cents • Twenty five cents D) 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 ! • That’s right “12” , • 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 !