1. Today we will be learning about Rounding Decimals numbers .
Good Afternoon!
Today we will be learning about
Rounding Decimals numbers .
Let’s warm up :
Convert the given Fraction to a Decimal valve?
1) 2/5
2) 2/3
Convert the given Decimal valve to a Fraction?
3) 0.45
4) 0.6
5) 2.5
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2. Review
Let’s review what we did in the last session.
FRACTION : A number that names part of a whole or part of a group.
¼ means 1 part of 4 parts, where 4 parts is the whole or group.
DENOMINATOR: It is the number below the bar in a fraction.
NUMERATOR: It is the number above the bar in a fraction.
NUMERATOR
FRACTION
DENOMINATOR
MIXED NUMBERS : A number named by a whole number and a fraction.
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3. Write a fraction to show what part of the rectangle is pink.
Review
Identifying, reading and writing a fraction
Write a fraction to show what part of the rectangle is pink.
NUMERATOR
Pink part: 4
Equal parts in all: 7
DENOMINATOR
So, 4 of the area is pink. 7
The fraction will be read as Four-sevenths.
Write a fraction to show what part of the rectangle is blue.
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4. We can show decimal numbers with the help of a square grid model.
Review
We can show decimal numbers with the help of a square grid model.
These grids represent 1 and 25 hundredths, 1.25, and 1
. or 1
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5. Decimal numbers are another way to write fractions or mixed numbers.
Review
How do we get Fraction from Decimal?
Decimal numbers are another way to write fractions or mixed numbers.
We will be using place value to do this one!
Count the decimal places of the decimal starting from the decimal point.
If there is one decimal place, place the number over 10 and reduce.
If there are two decimal places, place the number over 100 and reduce.
If there are three decimal places, place the number over 1000 and reduce.
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6. How do we get Fraction to Decimal?
Review
How do we get Fraction to Decimal?
Divide the denominator (the bottom of the fraction) into the numerator (the top of the fraction).
Place a decimal point after the number inside the division "box" and attach as many zeros as necessary to handle the division.
If the quotient does not come out evenly, follow any rounding instructions.
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7. Identifying Equivalent Decimals and Fractions
Decimals are a type of fractional number. The decimal 0.5 represents the fraction 5/10.
The decimal 0.25 represents the fraction 25/100.
We know that 5/10 is equivalent to ½.
Here, ½ X 5/5 is 5/10
Again, the decimal 0.5 is equivalent to ½ or 2/4, etc. .
Some common Equivalent Decimals and Fractions:
0.1 and 1/10
0.2 and 1/5
0.5 and 1/2
0.25 and 1/4
0.50 and 1/2
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8. Rounding decimals numbers.
Let’s get started.
Rounding decimals numbers.
Estimating, or being able to guess and come close to a correct answer, is an important part of mathematics and a very handy tool for everyday life.
Rounding off is a kind of estimating.
Rounding decimals is very similar to rounding other numbers.
The only difference is that the place value of the digits to the right of the decimal point are different.
A decimal number is rounded to the whole number to which it is the nearest.
A decimal number is rounded to get the estimated value of that number.
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9. We can round a decimal number with the help of a number line.
Round 3.4 to the nearest whole number.
3.4
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
The number 3.4 is closer to 3 than it is to 4.
So, the rounded value of 3.4 is 3.
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10. We can round a decimal number using place value
To round off decimals:
1) Find the place value you want (the "rounding digit") and look at the digit just to the right of it.
2) If that digit is less than 5, do not change the rounding digit but drop all digits to the right of it.
3) If that digit is greater than or equal to five, add one to the rounding digit and drop all digits to the right of it.
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11. Round 12.67 to the nearest tenth.
STEP 1:
Look at the digit in the place to the right of where you want to round.
12.67
STEP 2:
If it is less than 5 round down.
If it is 5 or greater than 5, round up.
12.7
Round up to 12.7.
Hence, the rounded value of to the nearest tenth is 12.7.
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12. To round 75.9876 to the nearest hundredths.
1) Find the rounding digit first.
2) This is the "8".
We are trying to get rid of the all the digits to the right of the 8, but the result should be as accurate as possible.
3) Now look one digit to the right, at the digit in the thousandths place which is “7".
4) See that 7 is more than 5, Add one to the rounding digit and change all the rest of the digits to the right of it to zero. so the number "8" is incremented to “9”.
75.99
Hence, the rounded value of to the nearest hundredths is 75.99
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13. To round the number 47.5434 to the nearest thousandths.
1) Find the rounding digit first.
2) This is the “3".
We are trying to get rid of the all the digits to the right of the 3, but the result should be as accurate as possible.
3) Now look one digit to the right, at the digit in the ten-thousandths place which is “4".
4) See that 4 is less than 5, so leave the number “3" as it is, and drop the digits to the right of 3.
47.543
Hence, the rounded value of to the nearest hundredths is
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14. BREAK
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15. Click on the link below for some exciting puzzle
GAME
Click on the link below for some exciting puzzle
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16. Round to the nearest whole number:
Assignments
Round to the nearest whole number:
1) 6.78
2) 14.12
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17. 3) Robby walked 3.78 miles. To the nearest mile, how much did Robby walk?
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18. Round to the nearest tenths:
4) 85.73
5) 38.37
6) 7.13
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19. Round to the nearest hundredths:7)
8) 6.727
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20. Round to the nearest thousandths:9)
10)
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21. Let’s Review what we did today
Estimating, or being able to guess and come close to a correct answer, is an important part of mathematics and a very handy tool for everyday life.
Rounding off is a kind of estimating.
We can round a decimal number with the help of a number line.
Round 3.4 to the nearest whole number.
3.4
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
The number 3.4 is closer to 3 than it is to 4.
So, the rounded value of 3.4 is 3.
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22. We can round a decimal number using place value
Review
We can round a decimal number using place value
To round off decimals:
1) Find the place value you want (the "rounding digit") and look at the digit just to the right of it.
2) If that digit is less than 5, do not change the rounding digit but drop all digits to the right of it.
3) If that digit is greater than or equal to five, add one to the rounding digit and drop all digits to the right of it.
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23. To round 75.9876 to the nearest hundredths.
1) Find the rounding digit first.
2) This is the "8".
We are trying to get rid of the all the digits to the right of the 8, but the result should be as accurate as possible.
3) Now look one digit to the right, at the digit in the thousandths place which is “7".
4) See that 7 is more than 5, Add one to the rounding digit and change all the rest of the digits to the right of it to zero. so the number "8" is incremented to “9”.
75.99
Hence, the rounded value of to the nearest hundredths is 75.99
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24. See you in the next session.
You have done a nice job.
See you in the next session.
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