front end & rounding gwendolyn best suffolk public schools
TRANSCRIPT
Front End&
RoundingGwendolyn Best
Suffolk Public Schools
Estimation
The next few slides
will help you
test your
estimation skills.
Can I buy three for $100?
45
Can I buy three for $100?
$23
Can I buy 5 for $50?
The basketball would have to cost ______ or less for me to purchase five of them for $50.
Can I buy three for $20?
$4.95
Roundingto the highest
Place Value
Round each number to its highest
possible place value. Some
numbers will be rounded to ten-
thousands, thousands, hundreds,
or tens.
375+ 26 + 1,427 + 216
375 Hundreds
26 Tens
1,427 Thousands
216 Hundreds
Round to the highest place.
375 Hundreds 400
26 Tens 30
1,427 Thousands 1,000
216 Hundreds 200
After you round, add the numbers!
400
30
1000
+ 200
1630
8857
4758
7045
+ 2110
8857
4758
7045
+ 2110
9000
5000
7000
+ 2000
• Between 11,000 and 15,000
• Between 16,000 and 20,000
• Between 20,000 and 25,000
• Between 28,000 and 33,000
9000
5000
7000
+2000
247
6542
489
+ 92
247
6542
489
+ 92
200
7000
500
+ 90
200
7000
500
+ 90
• A little less than 7,000
• A little less than 8,000
• A little more than 8,000
• A little more than 10,000
5028
6732
1285
+ 835
5000
7000
1000
+ 800
5028
6732
1285
+ 835
Front End Estimation
FRONT ENDThe name of this strategy gives you a clue
about how it is used.
The word FRONT should remind you that you are only concerned with the front portion of the number.
Many people think this strategy is easier than rounding to the highest place value.
4,32 0
74 0
2,39 0
+ 2 0
4,329
748
2,398
+ 28
Draw a line through your list of numbers so that you have at least one digit from each addend in front of (before) the line.
Change all
numbers
after the line
to zeros.
All numbers
before the
line stay the
same.
375+ 26 + 1,427 + 216
375 37 026 2 0
1,427 1,42 0216 21 0
8857
4758
7045
+ 2110
8857
4758
7045
+ 2110
8000
4000
7000
+ 2000
8857
4758
7045
+ 2110
8857
4758
7045
+ 2110
8000
4000
7000
+ 2000
Draw the line after the first number
In each addend.
• Between 11,000 and 15,000
• Between 16,000 and 20,000
• Between 20,000 and 25,000
• Between 28,000 and 33,000
8000
4000
7000
+2000
247
6542
489
+ 92
247
6542
489
+ 92
240
6540
480
+ 90
Estimate to find the best answer.
240
6540
480
+ 90
• A little more than 7,000
• A little more than 8,000
• A little less than 9,000
• A little less than 10,0007350
5028
6732
1285
+ 835
5000
6700
1200
+ 800
5028
6732
1285
+ 835
Estimate and choose the most reasonable answer.
Between 11,000 and 15,000
Between 16,000 and 20,000
Between 20,000 and 25,000
Between 28,000 and 33,000
5000
6700
1200
+ 800
13700
3,876
5,814
3,176
+ 7,895
4,000
6,000
3,000
+ 8,000
3,000
5,000
3,000
+ 7,000
9,876
8,514
6,092
+ 3,895
9,000
8,000
6,000
+ 3,000
10,000
9,000
6,000
+ 4,000