1. Seminar 3
Welcome

2. Agenda Decimal/Fraction Notation
Addition, Subtraction, multiplication/division with Decimals

3.
4 tens + 2 ones + 3 tenths + 2 hundredths + 4 thousandths + 5 ten-thousandths
We read this number as
“Forty-two and three thousand two hundred forty-five ten-thousandths.”
The decimal point is read as “and”.

4. Write a word name for the number in this sentence: The top women’s time for the 50 yard freestyle is seconds.

5. Write a word name for the number in this sentence: The top women’s time for the 50 yard freestyle is seconds.
Twenty-two and sixty-two hundredths

6. To convert from decimal to fraction notation,
a) count the number of decimal
places,
b) move the decimal point that
many places to the right, and
c) write the answer over a
denominator with a 1 followed
by that number of zeros
4.98
2 places
4.98
Move
2 places.
2 zeros
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7. Write fraction notation for 0.924. Do not simplify.
0.924 =
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8. Write fraction notation for 0.924. Do not simplify.
Solution
0.924
0.924.
3 places
3 zeros
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9. Example D Write 17.77 as a fraction and as a mixed numeral.
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10. Example D Write 17.77 as a fraction and as a mixed numeral. Solution
To write as a fraction:
17.77
2 zeros
2 places
17.77
To write as a mixed numeral, we rewrite the whole number part and express the rest in fraction form:
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11. a) count the number of zeros, and
b) move the decimal point that
number of places to the left. Leave
off the denominator.
To convert from fraction notation to decimal notation when the denominator is 10, 100, 1000 and so on,
3 zeros
8.679.
Move
3 places.
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12. Example E Write decimal notation for
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13. Example E Write decimal notation for Solution 1 place 1 zero
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14. 1. In the number 623,841, which digit tells the number of 10 thousands?
Section 3.1
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15. 1. In the number 623,841, which digit tells the number of 10 thousands?
Section 3.1
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16. Section 3.1 2. Write a word name for 8.032.
a) Eight and thirty-two ten thousandths
b) Eight thousand, thirty-two
c) Eight and thirty-two hundredths
d) Eight and thirty-two thousandths
Section 3.1
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17. Section 3.1 2. Write a word name for 8.032.
a) Eight and thirty-two ten thousandths
b) Eight thousand, thirty-two
c) Eight and thirty-two hundredths
d) Eight and thirty-two thousandths
Section 3.1
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18. Section 3.1 3. Write decimal notation for a) 4.3 b) 0.53 c) 0.053
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19. Section 3.1 3. Write decimal notation for a) 4.3 b) 0.53 c) 0.053
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20. Adding with decimal notation is similar to adding whole numbers.
First we line up the decimal points so that we can add corresponding place-value digits.
Add the digits from the right.
If necessary, we can write extra zeros to the far right of the decimal point so that the number of places is the same.
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21. Example A
Add:
Solution Line up the decimal points and write extra zeros 1 8 . 6 5 6
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22. Example D
Subtract 574 – 3.825
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23. Example D Subtract 574 – 3.825 Solution 5 7 4 . 0 0 0 – 3 . 8 2 5 5 7 – 3 9 9 10 5 7 . 1 7 5
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24. 1. Add: a) b) c) d)
Section 3.2
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25. 1. Add: a) b) c) d)
Section 3.2
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26. Section 3.2 4. Subtract: 70 – 8.231. a) 61.231 b) 62.769 c) 62.231d)
Section 3.2
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27. Section 3.2 4. Subtract: 70 – 8.231. a) 61.231 b) 62.769 c) 62.231d)
Section 3.2
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28. To multiply using decimals: 0.8  0.43
a) Ignore the decimal points,
and multiply as though both
factors were whole numbers.
b) Then place the decimal point in
the result. The number of decimal
places in the product is the sum of the
number of places in the factors.
(count places from the right). 2
Ignore the decimal points for now.
(2 decimal places)
(1 decimal place)
(3 decimal places)
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29. To divide by a whole number; a) place the decimal point
directly above the decimal
point in the dividend, and
b) divide as though
dividing whole numbers.
Quotient
Dividend
Remainder
Divisor
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30. Review for Projects
A recipe for a drink calls for 1/5 quart water and ¾ quart apple juice.
How much liquid is needed?

31. 2/5 + 1/4 = 8/20 + 5/20 = 13/20
Now if the recipe is doubled?

32. 13/20
13/ /20 = 26/20 =1 6/20= 1 3/10 Or
13/20 * 2 = 13/20 *2/1 =26/20 = 1 6/20 =
1 3/10
If the recipe is halved?

33. 13/20
13/20 / 2 = 13/20 / 2/1 = 13/20 * ½= 13/40

34. Simplify and convert to decimal
2/5 x 1/6=

35. Simplify and convert to decimal
2/5 x 1/6= 3/30=1/10
Now change into decimal

36. 1/10 Simplest way is to use a calculator
First off, we'll interpret the fraction bar to mean "divided by." This means that 1/10 is the same as 1 divided by 10.
Now, we'll just do what the fraction bar says: divide 1.0 by 10:
And that's about it! 1/10 written as a decimal to 1 decimal places is 0.1.

37. Mileage
Molly bought gasoline when the odometer read 8, After the next filling, the odometer read 8, It took 9.8 gal to fill the tank.
a) How many miles did she drive?
b) How many miles per gallon (mpg) did the car get?

38. First Step Subtraction 8,999.9 8,678.9 321 .0 She drove 321 miles
Molly bought gasoline when the odometer read 8, After the next filling, the odometer read 8, It took 9.8 gal to fill the tank.
First Step Subtraction
8,999.9
8,678.9
She drove 321 miles
Next divide 321 by = 32.7 miles to the gallon.

39. Drew filled his truck’s gas tank and noted that the odometer read 62, After the next filling, the odometer read 63, It took 17.6 gal to fill the tank. How many miles per gallon did the truck get?

40. Drew filled his truck’s gas tank and noted that the odometer read 62, After the next filling, the odometer read 63, It took 17.6 gal to fill the tank. How many miles per gallon did the truck get?
/ 17.6 = 16.5