Transcript Rounding - TeacherWeb

Review Rounding
Write & Evaluate Expressions
Estimate Sums & Differences
Addition & Subtraction
1 0 0 ,0 0 0
1 0 ,0 0 0
1 ,0 0 0
100
10
1
Ten Billions
One Billions
Hundred Millions
Ten Millions
One Millions
Hundred Thousands
Ten Thousands
One Thousands
Hundreds
Tens
Ones
4
5
9
2
6
1
2
4
0
1
2
5
.
.1
.0 1
.0 0 1
.0 0 0 1
.0 0 0 0 1
Hundred
Thousandths
1 ,0 0 0 ,0 0 0
Ten Thousandths
1 0 ,0 0 0 ,0 0 0
One Thousandths
1 0 0 ,0 0 0 ,0 0 0
One Hundredths
1 ,0 0 0 ,0 0 0 ,0 0 0
One Tenths
1 0 ,0 0 0 ,0 0 0 ,0 0 0
Decimal Point
1 0 0 ,0 0 0 ,0 0 0 ,0 0 0
Hundred Billions
Find the Place Value and Round
.
4
6
3
7
8
<--Whole
Numbers
Part of
one (1)->
Equivalent
Fraction->
n/10
n/100 n/1000 n/10,000 n/100,000
Where do I look first?
• Round this number to the nearest hundred
368
Action
Increase by one or stays the same
Use rounding
• When the question asks
you to estimate.
Such as:
“about how many”…?
When an exact answer isn’t possible.
When an answer is difficult to obtain.
(Educated guessing for multiple choice)
Rounding Procedures
1. Draw an arrow pointing to
the place you are rounding.
(action)
2. Draw a dot (an eye) under
the digit to the right of the
place you are rounding.
Rounding Procedures
3. If the digit is 0-4, the number with
the arrow stays the same. The rest of
the numbers to the right change to 0’s.
4. If the digit is 5-9, the number
with the arrow rounds up one. The
rest of the numbers to the right turn to
0’s.
Rounding Rhyme
• Mark the place,
• Look to the right
• Four or less are out of sight
• Five and up
• Will buy one more,
• All those less, are out the door
• In those empty
• Right-hand spaces,
• Zeros keep the proper places
• Except in places less than a whole
• Such as the decimal case
• The last number is the last place
Ut ohhh!
5,621
5620
Oh yea! I’m moving
up Wahoo!
5,621
6,000
Every place to the right of
the arrow changes to zeros
No zero place holder
for me
2.88
2.9
Round to the nearest hundreds
place.
1-4 stay down
4,572
Answer 4,600
5-9 round up one
4,672
Answer 4,700
4,602
Answer 4,600
Round 2,593, 672 to the nearest
tens place.
1-4 stay down
5-9 round up one
2,593, 672
Answer 2,593,670
Round to the nearest tenth place.
1-4 stay down
5-9 round up one
4.572
Answer 4.600
4.672
Answer 4.700
4.602
Answer 4.600
Round each number to the place
that has an arrow.
1.
499
2.
923 ,749 ,072 ,345
923,749,100,000
3.
5, 289 .3259
5,289
4.
239 .0549
239.1
5.
27 .43
30
500
Practice Rounding
1)
2)
3)
4)
5)
6)
7)
269 (tens)
2.98 (ones)
3,146 (tens)
.912 (hundredths)
86,574 (ten thousands)
178.54 (hundreds)
411,990 (hundreds)
Answers
1)
2)
3)
4)
5)
6)
7)
270
269 (tens)
3
2.98 (ones)
3,l50
3,146 (tens)
.91
.912 (hundredths)
86,574 (ten thousands) 90,000
200.00
178.54 (hundreds)
412,000
411,990 (hundreds)
Round Numbers
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•
•
•
•
•
•
64
873
491
652
957
203
684
Answers
•
•
•
•
•
•
•
64
873
491
652
957
203
684
•
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•
•
•
•
•
60
870 or 900
490 or 500
650 or 700
960 or 1,000
200
680 or 700
Estimate Sums & Differences
• Round off both
numbers then add or
subtract.
55 + 61 = ?
60 + 60 = 120
691 – 54 = ?
700 – 50 = 650
Math Words
• Place-The position of
a digit in a number.
• Value- The product of
a digit multiplied by
its place.
• Standard Form-The
usual way to write a
number
• Expanded Form-A
way to write a number
as a sum of the
products of each digit
and its place.
• Whole number-any
one of the numbers 0,
1, 2, 3, 4, and so on.
Math Words
• Decimal-A number
with one or more
digits to the right of
the decimal point.
• Equivalent decimalsDecimals that name
the same number such
as .4, .40, .400
• Round-To find the
nearest value of a
number, based on the
given place.
• Estimate-To find a
number that is close
to the exact answer.
• Variable-A symbol
used to represent a
number or numbers
Math Words
• Algebraic Expression - • Evaluate or evaluation To find the value of an
A variable by itself or a
expression by
combination of one or
performing the operation
more variables, one or
or operations.
more operations, and
possibly one or more
numbers such as
For Example
n+2
n = 3, n + 2
3+2=5
Practice