Rounding Decimal Numbers

1

• Rounding Decimal Numbers

2
Reading Writing Decimal Numbers

• The first place to the right of the decimal is
  the tenths place.
• The next place is the hundredths place, and so
  on.

Lets finish our Whole Number Place Value cheat
sheet to include Decimal Number Place Values
3
How to Read Decimal Numbers

• Read the digits to the left of the decimal point
  in the same way you would read a whole number.

2. Read the decimal point as and.

• Read the digits to the right of the decimal point
  as if they formed a whole number

4. Name the place value of the last digit in the
number.
Nine million, six hundred five thousand, eight
hundred seventy-two
and
one
hundred forty-five thousand, six hundred
seventy-three
millionths
4
How to Write Decimal Numbers from Words

• Four thousand, twenty-three and fifty-six
  thousandths 4023.

4. Fill in the decimal part of the number by
writing that part after and so that its final
digit has the correct place value.
_
_
_
4,023.
5 6

• 5. If necessary, fill in any blank places between
  the decimal point and the number just written
  with zeros.

0
4,023.056
5
How to Write Decimal Numbers from Words

• Sixty thousand, five hundred and twelve
  hundred-thousandths

• Write the whole number part as usual.

60,500
2. Represent and with a decimal point.
60,500.
3. Find the place value of the first digit by
looking at the final word (place value).
hundred-thousandths
6
How to Write Decimal Numbers from Words

• Sixty thousand, five hundred and twelve
  hundred-thousandths 60,500.

4. Fill in the decimal part of the number by
writing that part after and so that its final
digit has the correct place value.
_
_
_
_
_
60,500.
1 2

• 5. If necessary, fill in any blank places between
  the decimal point and the number just written
  with zeros.

0
0
0
60,500.00012
7
Your Turn Use digits and a decimal point to
write each number.

• One hundred forty-six thousand, eleven and nine
  hundredths
• Twenty-two million, thirty-six thousand and
  thirteen hundred-thousandths
• One billion, five hundred sixty-seven million,
  two hundred fifty and three hundred eight
  thousandths

146,011.09
22,036,000.00013
1,567,000,250.308
8
Adding SubtractingDecimal Numbers

• Remember to line up the decimal places vertically
  to start on the right.
• a) 6.231 0.04 b) 6.23 0.044

1
2
1
1
6.231
6.23
0
0.04
0
0.044
1
7
2
.
6
6
8
1
.
6
9
Your Turn Add or Subtract as Indicated

• Remember to line up the decimal places
  vertically.
• a) 3.242 1.3631 b) 3.2421 1.363

4.6051
1.8791
10
Rounding Decimal Numbers

• a) Round 212.0165725 to the nearest
  ten-thousandth.

Step 1 Circle the number in the
ten-thousandths place.
212.0165725
Step 2 Write down all the numbers to the left
of the circle.
212.016
Step 3 If the number to the right of the circle
is 4 or less, then write the circled
number 5 or more, round the circled
number up
5 or more, round the circled number up
212.016
6
Step 4 Change the digits to the right of the
circle to zeros.
212.0166000
11
Rounding Decimal Numbers

• b) Round 4057.2138362 to two decimal places.

Step 1 Circle the number in the second decimal
place.
4057.2138362
Step 2 Write down all the numbers to the left
of the circle.
4057.2
Step 3 If the number to the right of the circle
is 4 or less, then write the circled
number 5 or more, round the circled
number up
4 or less, then write the circled number
4057.2
1
Step 4 Change the digits to the right of the
circle to zeros.
4057.2100000
12
Your Turn Round Each Number as Indicated

• Round 890.32825 to one decimal place.
• Round 76,098.9356 to the hundreds place.
• Round 2784.3691 to two decimal places.
• Round 158.397402 to the nearest thousandths
  place.
• Round 288.4256 to the nearest hundredths place.

890.3
76,100
2784.37
158.397
288.43